diff --git a/CHANGELOG.md b/CHANGELOG.md
index 77df0d292e..a02788b7ac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,13 @@
 
 You should also include the user name that made the change.
 -->
+## 13.x.x (unreleased)
+
+### Improvements
+- Server: UIのHTML（ノートなどの特別なページを除く）のキャッシュ時間を15秒から300秒に
+
+### Bugfixes
+-
 
 ## 13.5.3 (2023/02/09)
 
diff --git a/packages/backend/src/server/web/ClientServerService.ts b/packages/backend/src/server/web/ClientServerService.ts
index 1fa8950d75..46470246ef 100644
--- a/packages/backend/src/server/web/ClientServerService.ts
+++ b/packages/backend/src/server/web/ClientServerService.ts
@@ -337,7 +337,7 @@ export class ClientServerService {
 
 		const renderBase = async (reply: FastifyReply) => {
 			const meta = await this.metaService.fetch();
-			reply.header('Cache-Control', 'public, max-age=15');
+			reply.header('Cache-Control', 'public, max-age=300');
 			return await reply.view('base', {
 				img: meta.bannerUrl,
 				title: meta.name ?? 'Misskey',