diff --git a/app/assets/stylesheets/application.css b/app/assets/stylesheets/application.css
index 7a041441082..4fef301af23 100644
--- a/app/assets/stylesheets/application.css
+++ b/app/assets/stylesheets/application.css
@@ -102,6 +102,7 @@
 @import "./application/blocks/user/_completed-practices-progress.css";
 @import "./application/blocks/user/_following.css";
 @import "./application/blocks/user/_group-company-name.css";
+@import "./application/blocks/user/_mentor-memos.css";
 @import "./application/blocks/user/_niconico-calendar.css";
 @import "./application/blocks/user/_sns-links.css";
 @import "./application/blocks/user/_user-data.css";
diff --git a/app/assets/stylesheets/application/blocks/user/_mentor-memos.css b/app/assets/stylesheets/application/blocks/user/_mentor-memos.css
new file mode 100644
index 00000000000..f13aa717d7d
--- /dev/null
+++ b/app/assets/stylesheets/application/blocks/user/_mentor-memos.css
@@ -0,0 +1,82 @@
+.mentor-memo-list {
+  display: flex;
+  flex-direction: column;
+}
+
+.mentor-memo {
+  font-size: 0.875rem;
+  line-height: 1.6;
+}
+
+.mentor-memo__inner {
+  padding: 1rem;
+}
+
+@media (width <= 47.9375em) {
+  .mentor-memo__inner {
+    padding: 0.75rem;
+  }
+}
+
+.mentor-memo:not(:last-child) {
+  border-bottom: solid 1px var(--border-tint);
+}
+
+.mentor-memo__meta {
+  display: flex;
+  align-items: center;
+  gap: 0.375rem;
+  margin-bottom: 0.5rem;
+}
+
+.mentor-memo__writer-link {
+  display: inline-flex;
+  flex: 0 0 auto;
+  line-height: 1;
+}
+
+.mentor-memo__writer {
+  font-size: 0.875rem;
+  line-height: 1.4;
+  font-weight: 600;
+}
+
+.mentor-memo__created-at {
+  margin-left: auto;
+  font-size: 0.75rem;
+  line-height: 1.4;
+  white-space: nowrap;
+  color: var(--muted-text);
+}
+
+.mentor-memo__body {
+  margin-bottom: 0.5rem;
+}
+
+.mentor-memo__actions {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+}
+
+.mentor-memo__action {
+  font-size: 0.75rem;
+  line-height: 1;
+  display: inline-flex;
+  align-items: center;
+  gap: 0.25rem;
+  cursor: pointer;
+  background-color: transparent;
+  border: none;
+  padding: 0;
+  color: var(--muted-text);
+  transition: color 0.2s ease-in;
+}
+
+.mentor-memo__action:hover {
+  color: var(--link-text);
+}
+
+.mentor-memo__action.is-danger:hover {
+  color: var(--danger);
+}
diff --git a/app/controllers/api/mentor_memos_controller.rb b/app/controllers/api/mentor_memos_controller.rb
index 8d94f15fcd4..b8ff2647ed1 100644
--- a/app/controllers/api/mentor_memos_controller.rb
+++ b/app/controllers/api/mentor_memos_controller.rb
@@ -2,25 +2,55 @@
 
 class API::MentorMemosController < API::BaseController
   before_action :require_mentor_login_for_api
-  before_action -> { doorkeeper_authorize! :write }, only: %i[update], if: -> { doorkeeper_token.present? }
-  before_action -> { doorkeeper_authorize! :mentor }, only: %i[update], if: -> { doorkeeper_token.present? }
-  before_action :set_user, only: %i[update]
+  before_action -> { doorkeeper_authorize! :write }, only: %i[create update destroy], if: -> { doorkeeper_token.present? }
+  before_action -> { doorkeeper_authorize! :mentor }, only: %i[create update destroy], if: -> { doorkeeper_token.present? }
+  before_action :set_user, only: %i[create update destroy]
+  before_action :set_memo, only: %i[update destroy]
+  before_action :authorize_memo, only: %i[update destroy]
+
+  def create
+    memo = MentorMemo.new(mentor_memo_params)
+    memo.writer = current_user
+    memo.recipient = @user
+
+    if memo.save
+      render partial: 'users/mentor_memo', locals: { memo: }, status: :created
+    else
+      head :bad_request
+    end
+  end
 
   def update
-    if @user.update_mentor_memo(user_params[:mentor_memo])
+    if @mentor_memo.update(mentor_memo_params)
       head :ok
     else
       head :bad_request
     end
   end
 
+  def destroy
+    @mentor_memo.destroy
+
+    head :no_content
+  end
+
   private
 
   def set_user
-    @user = User.find(params[:id])
+    @user = User.find(params[:user_id])
+  end
+
+  def set_memo
+    @mentor_memo = @user.received_memos.find(params[:id])
   end
 
-  def user_params
-    params.require(:user).permit(:mentor_memo)
+  def mentor_memo_params
+    params.require(:mentor_memo).permit(:body)
+  end
+
+  def authorize_memo
+    return if @mentor_memo.writer == current_user || current_user.admin?
+
+    head :forbidden
   end
 end
diff --git a/app/controllers/products_controller.rb b/app/controllers/products_controller.rb
index 0b4df8b93e9..ec8253d3805 100644
--- a/app/controllers/products_controller.rb
+++ b/app/controllers/products_controller.rb
@@ -28,6 +28,7 @@ def show
     Footprint.find_or_create_for(@product, current_user)
     @footprints = Footprint.fetch_for_resource(@product)
     @comments = @product.comments.order(:created_at)
+    @mentor_memos = @product.user.received_memos.includes(:writer).order(created_at: :desc)
     respond_to do |format|
       format.html
       format.md
diff --git a/app/controllers/reports_controller.rb b/app/controllers/reports_controller.rb
index f0fb7ed671c..e3b67bd084f 100644
--- a/app/controllers/reports_controller.rb
+++ b/app/controllers/reports_controller.rb
@@ -25,6 +25,7 @@ def show
     @recent_reports = Report.list.where(user_id: @report.user.id).limit(10)
     Footprint.find_or_create_for(@report, current_user)
     @footprints = Footprint.fetch_for_resource(@report)
+    @mentor_memos = @report.user.received_memos.includes(:writer).order(created_at: :desc)
     respond_to do |format|
       format.html
       format.md
diff --git a/app/controllers/talks_controller.rb b/app/controllers/talks_controller.rb
index 31534a88ec9..481ad8d05e2 100644
--- a/app/controllers/talks_controller.rb
+++ b/app/controllers/talks_controller.rb
@@ -32,6 +32,7 @@ def index
   def show
     @comments = @talk.comments.order(:created_at)
     @reports = @user.reports.list.limit(20)
+    @mentor_memos = @user.received_memos.includes(:writer).order(created_at: :desc)
   end
 
   private
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 82f06aaa98b..8307c47332f 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -48,6 +48,8 @@ def show
     reports = @user.reports_with_learning_times
     @study_streak = StudyStreak.new(reports, include_wip: false)
 
+    @mentor_memos = @user.received_memos.includes(:writer).order(created_at: :desc)
+
     if logged_in?
       render :show
     else
diff --git a/app/javascript/importmap_application.js b/app/javascript/importmap_application.js
index 692368516d5..1c106e25421 100644
--- a/app/javascript/importmap_application.js
+++ b/app/javascript/importmap_application.js
@@ -49,7 +49,7 @@ import 'upload-image-to-article'
 import 'header-dropdown'
 import 'postal-code-address'
 import 'editor-selection-form'
-import 'user_mentor_memo'
+import 'mentor-memos'
 import 'invitation-url-updater'
 import 'movie-fileinput'
 import 'payment-methods-check-boxes'
diff --git a/app/javascript/initializeMentorMemo.js b/app/javascript/initializeMentorMemo.js
new file mode 100644
index 00000000000..9075f244267
--- /dev/null
+++ b/app/javascript/initializeMentorMemo.js
@@ -0,0 +1,134 @@
+import TextareaInitializer from 'textarea-initializer'
+import MarkdownInitializer from 'markdown-initializer'
+import { put, destroy } from '@rails/request.js'
+
+export default function initializeMemo(memo, userId) {
+  const memoId = memo.dataset.memo_id
+  const memoBody = memo.dataset.memo_body
+  let savedMemo = memoBody || ''
+
+  TextareaInitializer.initialize(`#js-memo-${memoId}`)
+  const markdownInitializer = new MarkdownInitializer()
+
+  const memoDisplay = memo.querySelector('.memo-display')
+  const memoDisplayContent = memo.querySelector('.memo-text')
+
+  const memoEditor = memo.querySelector('.memo-editor')
+  const editorTextarea = memo.querySelector('.a-markdown-input__textarea')
+  const editorPreview = memo.querySelector('.a-markdown-input__preview')
+
+  if (memoBody) {
+    memoDisplayContent.innerHTML = markdownInitializer.render(savedMemo)
+    editorPreview.innerHTML = markdownInitializer.render(savedMemo)
+  }
+
+  const editButton = memo.querySelector('.js-edit-memo')
+  if (editButton) {
+    editButton.addEventListener('click', () => {
+      toggleEditor()
+      resetEditorTabs()
+    })
+  }
+
+  const saveButton = memo.querySelector('.js-save-memo')
+  editorTextarea.addEventListener('input', () => {
+    saveButton.disabled = editorTextarea.value.trim().length === 0
+  })
+
+  saveButton.addEventListener('click', async () => {
+    try {
+      const editedMemo = editorTextarea.value
+      await updateMemo(memoId, editedMemo, userId)
+      savedMemo = editedMemo
+      toggleEditor()
+      memoDisplayContent.innerHTML = markdownInitializer.render(savedMemo)
+    } catch (error) {
+      console.warn(error)
+    }
+  })
+
+  const cancelButton = memo.querySelector('.js-cancel-memo')
+  cancelButton.addEventListener('click', () => {
+    toggleEditor()
+    editorTextarea.value = savedMemo
+    editorPreview.innerHTML = markdownInitializer.render(savedMemo)
+    saveButton.disabled = editorTextarea.value.trim().length === 0
+  })
+
+  const deleteButton = memo.querySelector('.js-delete-memo')
+  if (deleteButton) {
+    deleteButton.addEventListener('click', async () => {
+      if (window.confirm('本当によろしいですか？')) {
+        try {
+          await deleteMemo(memoId, userId)
+          memo.remove()
+
+          const mentorMemos = document.querySelector('.mentor-memos')
+          const emptyMessage = mentorMemos.querySelector('.o-empty-message')
+          const memoList = mentorMemos.querySelectorAll('.mentor-memo')
+
+          if (!memoList.length) emptyMessage.classList.remove('is-hidden')
+        } catch (error) {
+          console.warn(error)
+        }
+      }
+    })
+  }
+
+  const editorTab = memoEditor.querySelector('.editor-tab')
+  const editorTabContent = memoEditor.querySelector('.is-editor')
+  const previewTab = memoEditor.querySelector('.preview-tab')
+  const previewTabContent = memoEditor.querySelector('.is-preview')
+
+  const tabElements = [
+    editorTab,
+    editorTabContent,
+    previewTab,
+    previewTabContent
+  ]
+  editorTab.addEventListener('click', () =>
+    toggleClass(tabElements, 'is-active')
+  )
+  previewTab.addEventListener('click', () => {
+    editorPreview.innerHTML = markdownInitializer.render(editorTextarea.value)
+    toggleClass(tabElements, 'is-active')
+  })
+
+  async function updateMemo(memoId, memoContent, userId) {
+    const params = {
+      mentor_memo: {
+        body: memoContent
+      }
+    }
+    const response = await put(`/api/users/${userId}/mentor_memos/${memoId}`, {
+      body: params
+    })
+
+    if (!response.ok) throw new Error('Failed to update')
+  }
+
+  async function deleteMemo(memoId, userId) {
+    const response = await destroy(
+      `/api/users/${userId}/mentor_memos/${memoId}`
+    )
+
+    if (!response.ok) throw new Error('Failed to delete')
+  }
+
+  function toggleEditor() {
+    toggleClass([memoDisplay, memoEditor], 'is-hidden')
+  }
+
+  function toggleClass(elements, className) {
+    elements.forEach((element) => {
+      element.classList.toggle(className)
+    })
+  }
+
+  function resetEditorTabs() {
+    editorTab.classList.add('is-active')
+    editorTabContent.classList.add('is-active')
+    previewTab.classList.remove('is-active')
+    previewTabContent.classList.remove('is-active')
+  }
+}
diff --git a/app/javascript/initializeNewMentorMemo.js b/app/javascript/initializeNewMentorMemo.js
new file mode 100644
index 00000000000..658d60e4cb1
--- /dev/null
+++ b/app/javascript/initializeNewMentorMemo.js
@@ -0,0 +1,128 @@
+import TextareaInitializer from 'textarea-initializer'
+import MarkdownInitializer from 'markdown-initializer'
+import initializeMemo from './initializeMentorMemo'
+import { post } from '@rails/request.js'
+
+export default function initializeNewMemo(userId) {
+  TextareaInitializer.initialize('#js-new-memo')
+  const markdownInitializer = new MarkdownInitializer()
+
+  const mentorMemo = document.querySelector('.mentor-memos')
+
+  const memoDisplay = mentorMemo.querySelector('.memos-display')
+  const memoEditor = mentorMemo.querySelector('.new-memo-editor')
+
+  const memoEditorPreview = memoEditor.querySelector(
+    '.a-markdown-input__preview'
+  )
+  const editorTextarea = memoEditor.querySelector('.a-markdown-input__textarea')
+
+  const addButton = memoDisplay.querySelector('.js-add-memo')
+  const addContainer = memoDisplay.querySelector('.js-add-action')
+  const modalElements = [addContainer, memoEditor]
+  addButton.addEventListener('click', () => {
+    toggleClass(modalElements, 'is-hidden')
+    resetEditorTabs()
+    editorTextarea.focus()
+  })
+
+  const saveButton = memoEditor.querySelector('.js-save-memo')
+  saveButton.disabled = true
+  editorTextarea.addEventListener('input', () => {
+    saveButton.disabled = editorTextarea.value.trim().length === 0
+  })
+
+  const emptyMessage = memoDisplay.querySelector('.o-empty-message')
+  saveButton.addEventListener('click', async () => {
+    const memoContent = editorTextarea.value
+    const html = await createMemo(memoContent, userId)
+    if (!html) return
+
+    const newMemo = addNewMemo(html, userId)
+    newMemo.scrollIntoView()
+    closeEditor()
+
+    if (emptyMessage) {
+      emptyMessage.classList.add('is-hidden')
+    }
+  })
+
+  const cancelButton = memoEditor.querySelector('.js-cancel-memo')
+  cancelButton.addEventListener('click', () => {
+    closeEditor()
+  })
+
+  const editorTab = memoEditor.querySelector('.editor-tab')
+  const editorTabContent = memoEditor.querySelector('.is-editor')
+  const previewTab = memoEditor.querySelector('.preview-tab')
+  const previewTabContent = memoEditor.querySelector('.is-preview')
+
+  const tabElements = [
+    editorTab,
+    editorTabContent,
+    previewTab,
+    previewTabContent
+  ]
+
+  editorTab.addEventListener('click', () =>
+    toggleClass(tabElements, 'is-active')
+  )
+  previewTab.addEventListener('click', () => {
+    memoEditorPreview.innerHTML = markdownInitializer.render(
+      editorTextarea.value
+    )
+    toggleClass(tabElements, 'is-active')
+  })
+
+  function resetEditorTabs() {
+    editorTab.classList.add('is-active')
+    editorTabContent.classList.add('is-active')
+    previewTab.classList.remove('is-active')
+    previewTabContent.classList.remove('is-active')
+  }
+
+  function closeEditor() {
+    toggleClass(modalElements, 'is-hidden')
+    editorTextarea.value = ''
+    memoEditorPreview.innerHTML = ''
+    saveButton.disabled = true
+  }
+}
+
+async function createMemo(memo, userId) {
+  const params = {
+    mentor_memo: {
+      body: memo
+    }
+  }
+  try {
+    const response = await post(`/api/users/${userId}/mentor_memos/`, {
+      body: params
+    })
+
+    if (!response.ok) throw new Error('Failed to fetch')
+
+    return await response.text
+  } catch (error) {
+    console.warn(error)
+
+    return false
+  }
+}
+
+function addNewMemo(html, userId) {
+  const memoList = document.querySelector('.mentor-memo-list')
+  const memoDiv = document.createElement('div')
+  memoDiv.innerHTML = html
+  const newMemoElement = memoDiv.firstElementChild
+  memoList.prepend(newMemoElement)
+  initializeMemo(newMemoElement, userId)
+
+  return newMemoElement
+}
+
+function toggleClass(elements, className) {
+  elements.forEach((element) => {
+    element.classList.toggle(className)
+  })
+}
diff --git a/app/javascript/mentor-memos.js b/app/javascript/mentor-memos.js
new file mode 100644
index 00000000000..a5e68130196
--- /dev/null
+++ b/app/javascript/mentor-memos.js
@@ -0,0 +1,21 @@
+import initializeMemo from './initializeMentorMemo'
+import initializeNewMemo from './initializeNewMentorMemo'
+
+document.addEventListener('DOMContentLoaded', () => {
+  const mentorMemo = document.querySelector('.mentor-memos')
+  if (!mentorMemo) return
+
+  const userId = mentorMemo.dataset.user_id
+
+  const memos = mentorMemo.querySelectorAll('.mentor-memo')
+  const emptyMessage = mentorMemo.querySelector('.o-empty-message')
+  if (memos.length) {
+    memos.forEach((memo) => {
+      initializeMemo(memo, userId)
+    })
+  } else {
+    emptyMessage.classList.remove('is-hidden')
+  }
+
+  initializeNewMemo(userId)
+})
diff --git a/app/javascript/user_mentor_memo.js b/app/javascript/user_mentor_memo.js
deleted file mode 100644
index c124627f747..00000000000
--- a/app/javascript/user_mentor_memo.js
+++ /dev/null
@@ -1,147 +0,0 @@
-import CSRF from 'csrf'
-import TextareaInitializer from 'textarea-initializer'
-import MarkdownInitializer from 'markdown-initializer'
-
-document.addEventListener('DOMContentLoaded', () => {
-  const mentorMemo = document.querySelector('.user-mentor-memo')
-  if (mentorMemo) {
-    const markdownInitializer = new MarkdownInitializer()
-    const userId = mentorMemo.dataset.user_id
-    let savedMemo = ''
-
-    const memoDisplay = mentorMemo.querySelector('.memo-display')
-    const memoEditor = mentorMemo.querySelector('.memo-editor')
-
-    const placeholder = memoDisplay.querySelector('.a-placeholder')
-    const emptyMessage = memoDisplay.querySelector('.o-empty-message')
-    const memoDisplayContent = memoDisplay.querySelector(
-      '.user-mentor-memo-content'
-    )
-    const memoEditorPreview = memoEditor.querySelector(
-      '.a-markdown-input__preview'
-    )
-    const editorTextarea = memoEditor.querySelector(
-      '.a-markdown-input__textarea'
-    )
-
-    fetch(`/api/users/${userId}.json`, {
-      method: 'GET',
-      headers: {
-        'X-Requested-With': 'XMLHttpRequest'
-      },
-      credentials: 'same-origin',
-      redirect: 'manual'
-    })
-      .then((response) => {
-        return response.json()
-      })
-      .then((json) => {
-        if (json.mentor_memo) {
-          savedMemo = json.mentor_memo
-        }
-        placeholder.classList.add('is-hidden')
-        if (savedMemo.length === 0) {
-          emptyMessage.classList.remove('is-hidden')
-        } else {
-          memoDisplayContent.classList.remove('is-hidden')
-          editorTextarea.value = savedMemo
-          switchMemoDisplay(memoDisplay, savedMemo)
-          TextareaInitializer.initialize('#js-user-mentor-memo')
-          memoDisplayContent.innerHTML = markdownInitializer.render(savedMemo)
-          memoEditorPreview.innerHTML = markdownInitializer.render(savedMemo)
-        }
-      })
-      .catch((error) => {
-        console.warn(error)
-      })
-
-    const editButton = memoDisplay.querySelector('.card-footer-actions__action')
-    const modalElements = [memoDisplay, memoEditor]
-    editButton.addEventListener('click', () =>
-      toggleClass(modalElements, 'is-hidden')
-    )
-
-    const saveButton = memoEditor.querySelector('.is-primary')
-    saveButton.addEventListener('click', () => {
-      toggleClass(modalElements, 'is-hidden')
-      savedMemo = editorTextarea.value
-      updateMemo(savedMemo, userId)
-      memoDisplayContent.innerHTML = markdownInitializer.render(savedMemo)
-      TextareaInitializer.initialize('#js-user-mentor-memo')
-      switchMemoDisplay(memoDisplay, savedMemo)
-    })
-
-    const cancelButton = memoEditor.querySelector('.is-secondary')
-    cancelButton.addEventListener('click', () => {
-      toggleClass(modalElements, 'is-hidden')
-      editorTextarea.value = savedMemo
-      memoEditorPreview.innerHTML = markdownInitializer.render(savedMemo)
-      TextareaInitializer.initialize('#js-user-mentor-memo')
-    })
-
-    editorTextarea.addEventListener('change', () => {
-      memoEditorPreview.innerHTML = markdownInitializer.render(
-        editorTextarea.value
-      )
-      TextareaInitializer.initialize('#js-user-mentor-memo')
-    })
-
-    const editorTab = memoEditor.querySelector('.editor-tab')
-    const editorTabContent = memoEditor.querySelector('.is-editor')
-    const previewTab = memoEditor.querySelector('.preview-tab')
-    const previewTabContent = memoEditor.querySelector('.is-preview')
-
-    const tabElements = [
-      editorTab,
-      editorTabContent,
-      previewTab,
-      previewTabContent
-    ]
-    editorTab.addEventListener('click', () =>
-      toggleClass(tabElements, 'is-active')
-    )
-    previewTab.addEventListener('click', () =>
-      toggleClass(tabElements, 'is-active')
-    )
-  }
-})
-
-function updateMemo(memo, userId) {
-  const params = {
-    user: {
-      mentor_memo: memo
-    }
-  }
-  fetch(`/api/mentor_memos/${userId}`, {
-    method: 'PUT',
-    headers: {
-      'X-Requested-With': 'XMLHttpRequest',
-      'Content-Type': 'application/json; charset=utf-8',
-      'X-CSRF-Token': CSRF.getToken()
-    },
-    credentials: 'same-origin',
-    redirect: 'manual',
-    body: JSON.stringify(params)
-  })
-    .then((response) => {
-      return response
-    })
-    .catch((error) => {
-      console.warn(error)
-    })
-}
-
-function switchMemoDisplay(memoDisplay, memo) {
-  const memoDisplayContent = memoDisplay.querySelector(
-    '.user-mentor-memo-content'
-  )
-  const emptyMessage = memoDisplay.querySelector('.o-empty-message')
-  memoDisplayContent.classList.toggle('is-hidden', memo.length === 0)
-  emptyMessage.classList.toggle('is-hidden', memo.length !== 0)
-}
-
-function toggleClass(elements, className) {
-  elements.forEach((element) => {
-    element.classList.toggle(className)
-  })
-}
diff --git a/app/models/mentor_memo.rb b/app/models/mentor_memo.rb
new file mode 100644
index 00000000000..501df03d91d
--- /dev/null
+++ b/app/models/mentor_memo.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class MentorMemo < ApplicationRecord
+  belongs_to :recipient, class_name: 'User'
+  belongs_to :writer, class_name: 'User'
+
+  validates :body, presence: true
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index 353b06f6320..512096f2389 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -214,6 +214,18 @@ class User < ApplicationRecord # rubocop:todo Metrics/ClassLength
            dependent: :delete_all,
            inverse_of: 'user'
 
+  has_many :received_memos,
+           class_name: 'MentorMemo',
+           foreign_key: 'recipient_id',
+           inverse_of: :recipient,
+           dependent: :destroy
+
+  has_many :authored_memos,
+           class_name: 'MentorMemo',
+           foreign_key: 'writer_id',
+           inverse_of: :writer,
+           dependent: :destroy
+
   has_one_attached :avatar
   has_one_attached :profile_image
   has_one_attached :diploma_file
diff --git a/app/views/products/show.html.slim b/app/views/products/show.html.slim
index 6bbeb7caa13..ee52d3ab136 100644
--- a/app/views/products/show.html.slim
+++ b/app/views/products/show.html.slim
@@ -116,7 +116,7 @@ header.page-header
                 = render partial: 'reports/recent_reports',
                   locals: { header_display: true }
               .side-tabs-contents__item#side-tabs-content-2
-                = render 'users/user_mentor_memo', user_id: @product.user.id
+                = render 'users/user_mentor_memos', user_id: @product.user.id, memos: @mentor_memos
               .side-tabs-contents__item#side-tabs-content-3
                 .a-card
                   .user-data
diff --git a/app/views/reports/show.html.slim b/app/views/reports/show.html.slim
index f9be55fdbbb..91d2190b7e2 100644
--- a/app/views/reports/show.html.slim
+++ b/app/views/reports/show.html.slim
@@ -70,7 +70,7 @@
               .side-tabs-contents__item#side-tabs-content-1
                 = render partial: 'reports/recent_reports', locals: { header_display: false }
               .side-tabs-contents__item#side-tabs-content-2.is-only-mentor
-                = render 'users/user_mentor_memo', user_id: @report.user_id
+                = render 'users/user_mentor_memos', user_id: @report.user_id, memos: @mentor_memos
               .side-tabs-contents__item#side-tabs-content-3.is-only-mentor
                 .a-card
                   .user-data
diff --git a/app/views/talks/show.html.slim b/app/views/talks/show.html.slim
index 0b0c12c2b80..fde136f3ce0 100644
--- a/app/views/talks/show.html.slim
+++ b/app/views/talks/show.html.slim
@@ -81,7 +81,7 @@
                 .a-card
                   .user-data
                     .user-data__row
-                      = render 'users/user_mentor_memo', user_id: @user.id
+                      = render 'users/user_mentor_memos', user_id: @user.id, memos: @mentor_memos
                     .user-data__row
                       = render 'users/user_secret_attributes', user: @user
                     .user-data__row
diff --git a/app/views/users/_mentor_memo.html.slim b/app/views/users/_mentor_memo.html.slim
new file mode 100644
index 00000000000..414c331f976
--- /dev/null
+++ b/app/views/users/_mentor_memo.html.slim
@@ -0,0 +1,43 @@
+.mentor-memo data-memo_body="#{memo.body}" data-memo_id="#{memo.id}"
+  .memo-display
+    .mentor-memo__inner
+      .mentor-memo__meta
+        = render 'users/icon', user: memo.writer, image_class: 'mentor-memo__writer-icon is-xs', link_class: 'mentor-memo__writer-link'
+        a.mentor-memo__writer.a-text-link href="#{memo.writer.url}"
+          = memo.writer.login_name
+        time.mentor-memo__created-at
+          = l memo.created_at
+      .a-long-text.is-sm.memo-text.mentor-memo__body
+        = memo.body
+      - if memo.writer == current_user || current_user.admin?
+        .mentor-memo__actions
+          button.mentor-memo__action.js-edit-memo
+            i.fa-solid.fa-pen
+            | 編集
+          button.mentor-memo__action.is-danger.js-delete-memo
+            i.fa-solid.fa-trash-can
+            | 削除
+  .memo-editor.is-hidden
+    .form-tabs.js-tabs
+      .form-tabs__tab.js-tabs__tab.editor-tab.is-active
+        | メモ
+      .form-tabs__tab.js-tabs__tab.preview-tab
+        | プレビュー
+    .card-body
+      .card-body__description
+        .a-markdown-input.js-markdown-parent
+          .a-markdown-input__inner.is-editor.js-tabs__content.is-active
+            textarea.a-text-input.a-markdown-input__textarea id="js-memo-#{memo.id}" data-preview="#mentor-memo-preview-#{memo.id}" name='mentor_memo[body]'
+              = memo.body
+          .a-markdown-input__inner.is-preview.js-tabs__content
+            .a-long-text.is-md.a-markdown-input__preview
+    hr.a-border-tint
+    .card-footer
+      .card-main-actions
+        .card-main-actions__items
+          .card-main-actions__item
+            button.a-button.is-sm.is-primary.is-block.js-save-memo
+              | 保存する
+          .card-main-actions__item
+            button.a-button.is-sm.is-secondary.is-block.js-cancel-memo
+              | キャンセル
diff --git a/app/views/users/_user_mentor_memo.html.slim b/app/views/users/_user_mentor_memos.html.slim
similarity index 55%
rename from app/views/users/_user_mentor_memo.html.slim
rename to app/views/users/_user_mentor_memos.html.slim
index 1b6958ad946..5ca9a80915c 100644
--- a/app/views/users/_user_mentor_memo.html.slim
+++ b/app/views/users/_user_mentor_memos.html.slim
@@ -1,34 +1,28 @@
-section.a-card.is-memo.is-only-mentor.user-mentor-memo data-user_id=user_id
-  .memo-display
+section.a-card.is-memo.is-only-mentor.mentor-memos data-user_id=user_id
+  .memos-display
     .description
       header.card-header.is-sm
         h2.card-header__title
           | メンター向けユーザーメモ
       hr.a-border-tint
     .card-body
-      .card-body__description
-        .a-long-text.is-sm.a-placeholder
-          p
-          p
-          p
-          p
-          p
-          p
-        .o-empty-message.is-hidden
-          .o-empty-message__icon
-            i.fa-regular.fa-sad-tear
-          .o-empty-message__text
-            | ユーザーメモはまだありません。
-        .a-long-text.is-sm.user-mentor-memo-content.is-hidden
+      .mentor-memo-list
+        - memos.each do |memo|
+          = render partial: 'users/mentor_memo', locals: { memo: memo }
+      .o-empty-message.is-hidden
+        .o-empty-message__icon
+          i.fa-regular.fa-sad-tear
+        .o-empty-message__text
+          | ユーザーメモはまだありません。
     hr.a-border-tint
-    footer.card-footer
+    footer.card-footer.js-add-action
       .card-main-actions
         .card-main-actions__items
           .card-main-actions__item
-            button.card-footer-actions__action.a-button.is-sm.is-secondary.is-block
+            button.a-button.is-sm.is-secondary.is-block.js-add-memo
               i.fa-solid.fa-pen
-              | 編集
-  .memo-editor.is-hidden
+              | 追加
+  .new-memo-editor.is-hidden
     .form-tabs.js-tabs
       .form-tabs__tab.js-tabs__tab.editor-tab.is-active
         | メモ
@@ -38,7 +32,7 @@ section.a-card.is-memo.is-only-mentor.user-mentor-memo data-user_id=user_id
       .card-body__description
         .a-markdown-input.js-markdown-parent
           .a-markdown-input__inner.is-editor.js-tabs__content.is-active
-            textarea.a-text-input.a-markdown-input__textarea id='js-user-mentor-memo' data-preview='#user-mentor-memo-preview' name='user[memo]'
+            textarea.a-text-input.a-markdown-input__textarea id='js-new-memo' data-preview='#user-memo-preview' name='mentor_memo[body]'
           .a-markdown-input__inner.is-preview.js-tabs__content
             .a-long-text.is-md.a-markdown-input__preview
     hr.a-border-tint
@@ -46,8 +40,8 @@ section.a-card.is-memo.is-only-mentor.user-mentor-memo data-user_id=user_id
       .card-main-actions
         .card-main-actions__items
           .card-main-actions__item
-            button.a-button.is-sm.is-primary.is-block
+            button.a-button.is-sm.is-primary.is-block.js-save-memo
               | 保存する
           .card-main-actions__item
-            button.a-button.is-sm.is-secondary.is-block
+            button.a-button.is-sm.is-secondary.is-block.js-cancel-memo
               | キャンセル
diff --git a/app/views/users/show.html.slim b/app/views/users/show.html.slim
index 99a04dbf9ac..197f4f395e5 100644
--- a/app/views/users/show.html.slim
+++ b/app/views/users/show.html.slim
@@ -122,7 +122,7 @@
                       .o-empty-message__text
                         | 進路メモはまだありません。
           - if admin_or_mentor_login?
-            = render 'users/user_mentor_memo', user_id: @user.id
+            = render 'users/user_mentor_memos', user_id: @user.id, memos: @mentor_memos
 
         - if visible_learning_time_frames?(@user)
           .col-xs-12.col-lg-4.col-xxl-3
diff --git a/config/routes/api.rb b/config/routes/api.rb
index c3e5b0f57ec..ed4569e2324 100644
--- a/config/routes/api.rb
+++ b/config/routes/api.rb
@@ -40,6 +40,7 @@
     resources :mention_users, only: %i(index)
     resources :users, only: %i(index show update) do
       resource :support_context, only: %i(show), controller: 'users/support_contexts'
+      resources :mentor_memos, only: %i(create update destroy)
     end
     get "users/tags/:tag", to: "users#index", as: :users_tag, tag: /.+/
     resources :practices, only: %i(index show update) do
@@ -66,7 +67,6 @@
     namespace 'watches' do
       resources :toggle, only: %i(index)
     end
-    resources :mentor_memos, only: %i(update)
     resources :tags, only: %i(index update)
     resources :pages, only: %i(update)
     resources :questions, only: %i(index show update)
diff --git a/db/data/20260622000124_copy_user_mentor_memo_column_to_mentor_memos.rb b/db/data/20260622000124_copy_user_mentor_memo_column_to_mentor_memos.rb
new file mode 100644
index 00000000000..7ac32fff9d1
--- /dev/null
+++ b/db/data/20260622000124_copy_user_mentor_memo_column_to_mentor_memos.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CopyUserMentorMemoColumnToMentorMemos < ActiveRecord::Migration[8.1]
+  def up
+    pjord = User.find_by!(login_name: "pjord")
+    User.where.not(mentor_memo: [nil, ""] ).find_each do |user|
+      MentorMemo.create!(recipient: user, writer: pjord, body: "【2026年6月以前のメモ】\n#{user.mentor_memo}")
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end
diff --git a/db/migrate/20260126070916_create_mentor_memos.rb b/db/migrate/20260126070916_create_mentor_memos.rb
new file mode 100644
index 00000000000..f9970173e07
--- /dev/null
+++ b/db/migrate/20260126070916_create_mentor_memos.rb
@@ -0,0 +1,11 @@
+class CreateMentorMemos < ActiveRecord::Migration[8.1]
+  def change
+    create_table :mentor_memos do |t|
+      t.references :recipient, null: false, foreign_key: { to_table: :users }
+      t.references :writer, null: false, foreign_key: { to_table: :users }
+      t.text :body, null: false
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 2653c7d8e5a..54772193bd6 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -456,6 +456,16 @@
     t.index ["survey_question_id"], name: "index_linear_scales_on_survey_question_id"
   end
 
+  create_table "mentor_memos", force: :cascade do |t|
+    t.text "body", null: false
+    t.datetime "created_at", null: false
+    t.bigint "recipient_id", null: false
+    t.datetime "updated_at", null: false
+    t.bigint "writer_id", null: false
+    t.index ["recipient_id"], name: "index_mentor_memos_on_recipient_id"
+    t.index ["writer_id"], name: "index_mentor_memos_on_writer_id"
+  end
+
   create_table "micro_reports", force: :cascade do |t|
     t.bigint "comment_user_id"
     t.text "content", null: false
@@ -1149,6 +1159,8 @@
   add_foreign_key "learning_time_frames_users", "users"
   add_foreign_key "learning_times", "reports"
   add_foreign_key "linear_scales", "survey_questions"
+  add_foreign_key "mentor_memos", "users", column: "recipient_id"
+  add_foreign_key "mentor_memos", "users", column: "writer_id"
   add_foreign_key "micro_reports", "users"
   add_foreign_key "micro_reports", "users", column: "comment_user_id"
   add_foreign_key "movies", "users"
diff --git a/test/fixtures/users.yml b/test/fixtures/users.yml
index 91889968d96..98e6c1e3d3b 100644
--- a/test/fixtures/users.yml
+++ b/test/fixtures/users.yml
@@ -224,7 +224,6 @@ kimura:
   updated_at: "2014-01-01 00:00:07"
   created_at: "2014-01-01 00:00:07"
   last_activity_at: "2014-01-01 00:00:07"
-  mentor_memo: "kimuraさんのメモ"
   country_code: JP
   subdivision_code: '13'
   show_study_streak: true
diff --git a/test/models/user_test.rb b/test/models/user_test.rb
index 407f448daaa..58758ab7495 100644
--- a/test/models/user_test.rb
+++ b/test/models/user_test.rb
@@ -367,17 +367,6 @@ class UserTest < ActiveSupport::TestCase
     assert Following.find_by(follower_id: kimura.id, followed_id: hatsuno.id)
   end
 
-  test '#update_user_mentor_memo' do
-    user = users(:kimura)
-    assert_equal 'kimuraさんのメモ', user.mentor_memo
-    user.updated_at = Time.zone.local(2020, 1, 1, 0, 0, 0)
-    user.update_mentor_memo('新規メモ')
-    travel_to Time.zone.local(2020, 1, 1, 0, 0, 0) do
-      assert user.updated_at
-    end
-    assert_equal '新規メモ', user.mentor_memo
-  end
-
   test '.delayed when there are users within 2 weeks from completion of last practice' do
     user = users(:nippounashi)
     practice1 = practices(:practice1)
diff --git a/test/system/products/mentor_test.rb b/test/system/products/mentor_test.rb
index 5ca1d1ba03b..a89854a4564 100644
--- a/test/system/products/mentor_test.rb
+++ b/test/system/products/mentor_test.rb
@@ -38,42 +38,6 @@ class MentorTest < ApplicationSystemTestCase
       end
     end
 
-    test 'display the user memos after click on user-memos tab' do
-      visit_with_auth "/products/#{products(:product2).id}", 'komagata'
-      find('#side-tabs-nav-2').click
-      assert_text 'kimuraさんのメモ'
-    end
-
-    test 'can cancel editing of user-memos' do
-      visit_with_auth "/products/#{products(:product2).id}", 'komagata'
-      find('#side-tabs-nav-2').click
-      click_button '編集'
-      fill_in 'js-user-mentor-memo', with: '編集はできないはずです。'
-      click_button 'キャンセル'
-      assert_no_text '編集はできないはずです。'
-      assert_text 'kimuraさんのメモ'
-    end
-
-    test 'can preview editing of user-memos' do
-      visit_with_auth "/products/#{products(:product2).id}", 'komagata'
-      find('#side-tabs-nav-2').click
-      assert_text 'kimuraさんのメモ'
-      click_button '編集'
-      fill_in 'js-user-mentor-memo', with: 'プレビューができます。'
-      find('.form-tabs__tab', text: 'プレビュー').click
-      assert_text 'プレビューができます。'
-    end
-
-    test 'can update user-memos' do
-      visit_with_auth "/products/#{products(:product2).id}", 'komagata'
-      find('#side-tabs-nav-2').click
-      assert_text 'kimuraさんのメモ'
-      click_button '編集'
-      fill_in 'js-user-mentor-memo', with: '編集後のユーザーメモです。'
-      click_button '保存する'
-      assert_text '編集後のユーザーメモです。', wait: 10
-    end
-
     test 'display a list of products in side-column' do
       user = users(:kimura)
       visit_with_auth "/products/#{products(:product2).id}", 'mentormentaro'
diff --git a/test/system/talks/content_test.rb b/test/system/talks/content_test.rb
index 31160218e08..f0fa31e5f83 100644
--- a/test/system/talks/content_test.rb
+++ b/test/system/talks/content_test.rb
@@ -16,17 +16,6 @@ class ContentTest < ApplicationSystemTestCase
       assert_text 'ユーザー公開情報'
     end
 
-    test 'update memo' do
-      user = users(:kimura)
-      visit_with_auth "/talks/#{user.talk.id}", 'komagata'
-      assert_text 'kimuraさんのメモ'
-      click_button '編集'
-      fill_in 'js-user-mentor-memo', with: '相談部屋テストメモ'
-      click_button '保存する'
-      assert_text '相談部屋テストメモ'
-      assert_no_text 'kimuraさんのメモ'
-    end
-
     test 'Displays a list of the 10 most recent reports' do
       user = users(:hajime)
       visit_with_auth "/talks/#{user.talk.id}", 'komagata'
diff --git a/test/system/user/memos_test.rb b/test/system/user/memos_test.rb
index 0dcdea6b15e..50db23419df 100644
--- a/test/system/user/memos_test.rb
+++ b/test/system/user/memos_test.rb
@@ -3,26 +3,88 @@
 require 'application_system_test_case'
 
 class User::MemoTest < ApplicationSystemTestCase
-  test 'update memo' do
-    visit_with_auth user_path(users(:hatsuno)), 'komagata'
-    assert_text 'ユーザーメモはまだありません。'
-    click_button '編集'
-    fill_in 'js-user-mentor-memo', with: 'ユーザーメンターメモ'
+  setup do
+    @memo = MentorMemo.create!(
+      recipient: users(:kimura),
+      writer: users(:mentormentaro),
+      body: 'kimuraさんのメモ'
+    )
+  end
+
+  test 'add memo' do
+    visit_with_auth user_path(users(:kimura)), 'mentormentaro'
+    click_button '追加'
+    fill_in 'js-new-memo', with: '新しいメモ'
     click_button '保存する'
-    assert_text 'ユーザーメンターメモ'
-    assert_no_text 'ユーザーメモはまだありません。'
+    assert_text '新しいメモ'
+  end
+
+  test 'update memo' do
+    visit_with_auth user_path(users(:kimura)), 'mentormentaro'
+    assert_text 'kimuraさんのメモ'
+
+    within(".mentor-memo[data-memo_id='#{@memo.id}']") do
+      click_button '編集'
+      fill_in "js-memo-#{@memo.id}", with: '編集されたメモ'
+      click_button '保存する'
+    end
+    assert_text '編集されたメモ'
+    assert_no_text 'kimuraさんのメモ'
+  end
+
+  test 'delete memo' do
+    visit_with_auth user_path(users(:kimura)), 'mentormentaro'
+    assert_text 'kimuraさんのメモ'
+
+    within(".mentor-memo[data-memo_id='#{@memo.id}']") do
+      accept_confirm do
+        click_button '削除'
+      end
+    end
+    assert_no_text 'kimuraさんのメモ'
   end
 
-  test 'do not update memo when cancel' do
+  test 'admin can edit and delete others memo' do
     visit_with_auth user_path(users(:kimura)), 'komagata'
+    assert_button '編集'
+    assert_button '削除'
+  end
+
+  test 'non writer cannot edit or delete memo' do
+    visit_with_auth user_path(users(:kimura)), 'long-id-mentor'
+    assert_no_button '編集'
+    assert_no_button '削除'
+  end
+
+  test 'cancel editing does not update memo' do
+    visit_with_auth user_path(users(:kimura)), 'mentormentaro'
     assert_text 'kimuraさんのメモ'
-    assert_no_text 'ユーザーメモはまだありません。'
-    click_button '編集'
-    fill_in 'js-user-mentor-memo', with: 'ユーザーメンターメモ'
-    click_button 'キャンセル'
-    assert_no_text 'ユーザーメンターメモ'
+
+    within(".mentor-memo[data-memo_id='#{@memo.id}']") do
+      click_button '編集'
+      fill_in "js-memo-#{@memo.id}", with: '編集されたメモ'
+      click_button 'キャンセル'
+    end
     assert_text 'kimuraさんのメモ'
-    assert_no_text 'ユーザーメモはまだありません。'
+    assert_no_text '編集されたメモ'
+  end
+
+  test 'can preview while editing memo' do
+    visit_with_auth user_path(users(:kimura)), 'mentormentaro'
+    assert_text 'kimuraさんのメモ'
+
+    within(".mentor-memo[data-memo_id='#{@memo.id}']") do
+      click_button '編集'
+      fill_in "js-memo-#{@memo.id}", with: 'プレビューができます。'
+      find('.form-tabs__tab', text: 'プレビュー').click
+    end
+    assert_text 'プレビューができます。'
+  end
+
+  test 'show empty message when no memos' do
+    visit_with_auth user_path(users(:hajime)), 'mentormentaro'
+    assert_text 'ユーザーメモはまだありません。'
+    assert_no_selector '.mentor-memo'
   end
 
   test 'admin can see memo' do