diff --git a/docs/thank-you.md b/docs/thank-you.md
new file mode 100644
index 0000000..29daf40
--- /dev/null
+++ b/docs/thank-you.md
@@ -0,0 +1,14 @@
+---
+layout: page
+title: Thank You for Using Copy for Scrapbox!
+---
+
+# Thank you for Using Copy for Scrapbox!
+
+We are sorry to see you go! Your feedback is important to us.
+Please take a moment to let us know why you decided to uninstall the extension.
+
+- [GitHub Issues](https://github.com/satoryu/copy-for-scrapbox/issues)
+- Email: satoryu.1981@gmail.com
+
+Thank you for your time and feedback!
diff --git a/src/background.js b/src/background.js
index c66eac4..f2029e8 100644
--- a/src/background.js
+++ b/src/background.js
@@ -1,10 +1,12 @@
 import { getClientId } from './id.js'
-import { sendTrackEvent } from './google-analytics.js'
+import { installationHandler } from './installation-handler.js'
 import contextMenuRepository from './context_menu'
 
-chrome.runtime.onInstalled.addListener(function () {
+chrome.runtime.onInstalled.addListener(function ({ previousVersion, reason }) {
   getClientId()
-  sendTrackEvent({ name: 'installed' })
+    .then((_clientId) => installationHandler({ previousVersion, reason }))
+
+  chrome.runtime.setUninstallURL('https://www.satoryu.com/copy-for-scrapbox/thank-you')
 
   contextMenuRepository.getContextMenuInfo().forEach((contextMenuInfo) => {
     chrome.contextMenus.create(contextMenuInfo)
diff --git a/src/google-analytics.js b/src/google-analytics.js
index 0fd8eb4..afb9ee5 100644
--- a/src/google-analytics.js
+++ b/src/google-analytics.js
@@ -11,6 +11,8 @@ async function sendTrackEvent(event) {
     engagement_time_msec: 100
   }
 
+  console.debug('Sending event:', event);
+
   return fetch(
     `${GA_ENDPOINT}?measurement_id=${MEASUREMENT_ID}&api_secret=${API_SECRET}`,
     {
diff --git a/src/installation-handler.js b/src/installation-handler.js
new file mode 100644
index 0000000..0e2c556
--- /dev/null
+++ b/src/installation-handler.js
@@ -0,0 +1,35 @@
+import { sendTrackEvent } from "./google-analytics"
+
+async function saveLastInstalledVersion() {
+  const { version } = chrome.runtime.getManifest()
+
+  return chrome.storage.local.set({ lastInstalledVersion: version })
+}
+
+async function getLastInstalledVersion() {
+  return chrome.storage.local.get('lastInstalledVersion')
+    .then(({ lastInstalledVersion }) => lastInstalledVersion)
+}
+
+export async function installationHandler({ previousVersion, reason }) {
+  const { version } = chrome.runtime.getManifest()
+
+  if (reason === 'install') {
+    await sendTrackEvent({ name: 'installed', params: { version } })
+      .then(saveLastInstalledVersion)
+      .then(() => console.debug(`lastInstalledVersion is set: ${version}`))
+  } else if (reason === 'update') {
+    await getLastInstalledVersion()
+    .then((lastInstalledVersion) => {
+      // if already installed, just update the version
+      if (lastInstalledVersion) {
+        console.debug(`lastInstalledVersion is ${lastInstalledVersion}`)
+        sendTrackEvent({ name: 'updated', params: { version, previousVersion } })
+        return
+      }
+
+      sendTrackEvent({ name: 'installed', params: { version } })
+        .then(saveLastInstalledVersion)
+    })
+  }
+}
\ No newline at end of file
diff --git a/test/installation-hander.test.js b/test/installation-hander.test.js
new file mode 100644
index 0000000..0ac4662
--- /dev/null
+++ b/test/installation-hander.test.js
@@ -0,0 +1,51 @@
+import { installationHandler } from "../src/installation-handler.js"
+import { sendTrackEvent } from "../src/google-analytics.js"
+
+global.chrome = {
+  runtime: {
+    getManifest: () => ({ version: '4.4.4' })
+  },
+  storage: {
+    local: {
+      set: jest.fn(() => Promise.resolve()),
+      get: jest.fn(() => Promise.resolve({})),
+    },
+  }
+}
+
+jest.mock('../src/google-analytics.js', () => ({ sendTrackEvent: jest.fn() }))
+
+describe('installationHandler', () => {
+  beforeEach(() => {
+    chrome.storage.local.set.mockClear()
+    sendTrackEvent.mockClear()
+
+    sendTrackEvent.mockReturnValue(Promise.resolve())
+  })
+
+  describe('When the reason is install', () => {
+    it('should send installed event to google analytics', async () => {
+      await installationHandler({ reason: 'install' })
+
+      expect(sendTrackEvent).toHaveBeenCalledWith({ name: 'installed', params: { version: '4.4.4' } })
+      expect(chrome.storage.local.set).toHaveBeenCalledWith({ lastInstalledVersion: '4.4.4' })
+    })
+  })
+
+  describe('When the reason is update', () => {
+    it('should send updated event to google analytics', async () => {
+      chrome.storage.local.get.mockReturnValue(Promise.resolve({ lastInstalledVersion: '3.3.3' }))
+      await installationHandler({ reason: 'update', previousVersion: '4.4.3' })
+
+      expect(sendTrackEvent).toHaveBeenCalledWith({ name: 'updated', params: { version: '4.4.4', previousVersion: '4.4.3' } })
+      expect(chrome.storage.local.set).not.toHaveBeenCalled()
+    })
+
+    it('should send installed event if latestInstalledVersion is not set', async () => {
+      chrome.storage.local.get.mockReturnValue(Promise.resolve({ lastInstalledVersion: null }))
+      await installationHandler({ reason: 'update', previousVersion: '4.4.3' })
+
+      expect(sendTrackEvent).toHaveBeenCalledWith({ name: 'installed', params: { version: '4.4.4' } })
+    })
+  })
+})