diff --git a/packages/frontend/src/style.scss b/packages/frontend/src/style.scss
index 32f2b5ef3d..12879e63b3 100644
--- a/packages/frontend/src/style.scss
+++ b/packages/frontend/src/style.scss
@@ -92,7 +92,7 @@ html {
 
 html._themeChangingFallback_ {
 	&, * {
-		transition: background 1s ease, border 1s ease !important;
+		transition: background 0.5s ease, border 0.5s ease !important;
 	}
 }
 
@@ -102,13 +102,13 @@ html._themeChanging_ {
 
 html::view-transition-new(theme-changing) {
 	z-index: 4000001;
-	animation: themeChangingNew 1s ease;
+	animation: themeChangingNew 0.5s ease;
 	animation-fill-mode: forwards;
 }
 
 html::view-transition-old(theme-changing) {
 	z-index: 4000000;
-	animation: themeChangingOld 1s ease;
+	animation: themeChangingOld 0.5s ease;
 	animation-fill-mode: forwards;
 }
 
diff --git a/packages/frontend/src/theme.ts b/packages/frontend/src/theme.ts
index 003fd8b6f0..9562f69cf3 100644
--- a/packages/frontend/src/theme.ts
+++ b/packages/frontend/src/theme.ts
@@ -141,18 +141,17 @@ export function applyTheme(theme: Theme, persist = true) {
 			await nextTick();
 		}).finished.then(() => {
 			window.document.documentElement.classList.remove('_themeChanging_');
+			// 色計算など再度行えるようにクライアント全体に通知
 			globalEvents.emit('themeChanged');
 		});
 	} else {
 		// TODO: ViewTransition API が主要ブラウザで対応したら消す
-
 		window.document.documentElement.classList.add('_themeChangingFallback_');
 		timeout = window.setTimeout(() => {
 			window.document.documentElement.classList.remove('_themeChangingFallback_');
-
 			// 色計算など再度行えるようにクライアント全体に通知
 			globalEvents.emit('themeChanged');
-		}, 1000);
+		}, 500);
 
 		applyThemeInternal(theme, persist);
 	}