diff --git a/CHANGELOG.md b/CHANGELOG.md
index e767c15df4..e236006afb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,11 @@
 You should also include the user name that made the change.
 -->
 
+## 13.x.x (unreleased)
+
+### Bugfixes
+- Client: classicモード使用時にwindowサイズによってdefaultに変更された後に、windowサイズが元に戻ったらclassicに戻すように修正 #9669
+
 ## 13.2.4 (2023/01/27)
 ### Improvements
 - リモートカスタム絵文字表示時のパフォーマンスを改善
diff --git a/packages/frontend/src/local-storage.ts b/packages/frontend/src/local-storage.ts
index 68dc9ebe41..e6b828696c 100644
--- a/packages/frontend/src/local-storage.ts
+++ b/packages/frontend/src/local-storage.ts
@@ -18,6 +18,7 @@ type Keys =
 	'useSystemFont' | 
 	'fontSize' |
 	'ui' |
+	'ui_temp' |
 	'locale' |
 	'localeVersion' |
 	'theme' |
diff --git a/packages/frontend/src/ui/classic.vue b/packages/frontend/src/ui/classic.vue
index dab4b9b274..a5c2f8ca23 100644
--- a/packages/frontend/src/ui/classic.vue
+++ b/packages/frontend/src/ui/classic.vue
@@ -124,6 +124,8 @@ function onAiClick(ev) {
 }
 
 if (window.innerWidth < 1024) {
+	const currentUI = miLocalStorage.getItem('ui')
+	miLocalStorage.setItem('ui_temp', currentUI || 'default');
 	miLocalStorage.setItem('ui', 'default');
 	location.reload();
 }
diff --git a/packages/frontend/src/ui/universal.vue b/packages/frontend/src/ui/universal.vue
index babc232875..a9bb85ab6a 100644
--- a/packages/frontend/src/ui/universal.vue
+++ b/packages/frontend/src/ui/universal.vue
@@ -141,6 +141,15 @@ mainRouter.on('change', () => {
 
 document.documentElement.style.overflowY = 'scroll';
 
+if (window.innerWidth > 1024) {
+	const tempUI = miLocalStorage.getItem('ui_temp')
+	if (tempUI) {
+		miLocalStorage.setItem('ui', tempUI)
+		miLocalStorage.removeItem('ui_temp')
+		location.reload();
+	}
+}
+
 defaultStore.ready.then(() => {
 	if (defaultStore.state.widgets.length === 0) {
 		defaultStore.set('widgets', [{