diff --git a/packages/frontend/lib/vite-plugin-watch-locales.ts b/packages/frontend/lib/vite-plugin-watch-locales.ts
new file mode 100644
index 0000000000..8e209d27bd
--- /dev/null
+++ b/packages/frontend/lib/vite-plugin-watch-locales.ts
@@ -0,0 +1,36 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import path from 'node:path'
+import locales from '../../../locales/index.js';
+
+const localesDir = path.resolve(__dirname, '../../../locales')
+
+/**
+ * 外部ファイルを監視し、必要に応じてwebSocketでメッセージを送るViteプラグイン
+ * @returns {import('vite').Plugin}
+ */
+export default function pluginWatchLocales() {
+  return {
+    name: 'watch-locales',
+
+    configureServer(server) {
+      const localeYmlPaths = Object.keys(locales).map(locale => path.join(localesDir, `${locale}.yml`));
+
+      // watcherにパスを追加
+      server.watcher.add(localeYmlPaths);
+
+			server.watcher.on('change', (filePath) => {
+				if (localeYmlPaths.includes(filePath)) {
+					server.ws.send({
+						type: 'custom',
+						event: 'locale-update',
+						data: filePath.match(/([^\/]+)\.yml$/)?.[1] || null,
+					})
+				}
+			});
+    },
+  };
+}
diff --git a/packages/frontend/src/boot/common.ts b/packages/frontend/src/boot/common.ts
index c8098b6cf8..992bde9bd1 100644
--- a/packages/frontend/src/boot/common.ts
+++ b/packages/frontend/src/boot/common.ts
@@ -81,8 +81,10 @@ export async function common(createVue: () => Promise<App<Element>>) {
 	//#region Detect language & fetch translations
 	const localeVersion = miLocalStorage.getItem('localeVersion');
 	const localeOutdated = (localeVersion == null || localeVersion !== version || locale == null);
-	if (localeOutdated) {
-		const res = await window.fetch(`/assets/locales/${lang}.${version}.json`);
+
+	async function fetchAndUpdateLocale({ useCache } = { useCache: true }) {
+		const fetchOptions: RequestInit | undefined = useCache ? undefined : { cache: 'no-store' };
+		const res = await window.fetch(`/assets/locales/${lang}.${version}.json`, fetchOptions);
 		if (res.status === 200) {
 			const newLocale = await res.text();
 			const parsedNewLocale = JSON.parse(newLocale);
@@ -92,6 +94,23 @@ export async function common(createVue: () => Promise<App<Element>>) {
 			updateI18n(parsedNewLocale);
 		}
 	}
+
+	if (localeOutdated) {
+		fetchAndUpdateLocale();
+	}
+
+	if (import.meta.hot) {
+		import.meta.hot.on('locale-update', async (updatedLang: string) => {
+			console.info(`Locale updated: ${updatedLang}`);
+			if (updatedLang === lang) {
+				await new Promise(resolve => {
+					window.setTimeout(resolve, 500);
+				});
+				await fetchAndUpdateLocale({ useCache: false });
+				window.location.reload();
+			}
+		});
+	}
 	//#endregion
 
 	// タッチデバイスでCSSの:hoverを機能させる
diff --git a/packages/frontend/vite.config.ts b/packages/frontend/vite.config.ts
index b0ccbfb65c..77b5b48a18 100644
--- a/packages/frontend/vite.config.ts
+++ b/packages/frontend/vite.config.ts
@@ -13,6 +13,7 @@ import pluginUnwindCssModuleClassName from './lib/rollup-plugin-unwind-css-modul
 import pluginJson5 from './vite.json5.js';
 import pluginCreateSearchIndex from './lib/vite-plugin-create-search-index.js';
 import type { Options as SearchIndexOptions } from './lib/vite-plugin-create-search-index.js';
+import pluginWatchLocales from './lib/vite-plugin-watch-locales.js';
 
 const url = process.env.NODE_ENV === 'development' ? yaml.load(await fsp.readFile('../../.config/default.yml', 'utf-8')).url : null;
 const host = url ? (new URL(url)).hostname : undefined;
@@ -102,6 +103,7 @@ export function getConfig(): UserConfig {
 		},
 
 		plugins: [
+			pluginWatchLocales(),
 			...searchIndexes.map(options => pluginCreateSearchIndex(options)),
 			pluginVue(),
 			pluginUnwindCssModuleClassName(),