diff --git a/CHANGELOG.md b/CHANGELOG.md
index 445dfb5aae..52e18271a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,9 @@
 ### Server
 - Enhance: `clips/my-favorites` APIがページネーションに対応しました
 - Enhance: メモリ使用量を削減しました
+- Fix: DeepL APIのAPIキー指定方式変更に対応  
+  (Cherry-picked from https://github.com/MisskeyIO/misskey/pull/1096)
+	- 内部実装の変更にて対応可能な更新です。Misskey側の設定方法に変更はありません。
 
 ## 2025.11.0
 
diff --git a/packages/backend/src/server/api/endpoints/notes/translate.ts b/packages/backend/src/server/api/endpoints/notes/translate.ts
index e9a6a36b02..cd7d46007c 100644
--- a/packages/backend/src/server/api/endpoints/notes/translate.ts
+++ b/packages/backend/src/server/api/endpoints/notes/translate.ts
@@ -95,7 +95,6 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			if (targetLang.includes('-')) targetLang = targetLang.split('-')[0];
 
 			const params = new URLSearchParams();
-			params.append('auth_key', this.serverSettings.deeplAuthKey);
 			params.append('text', note.text);
 			params.append('target_lang', targetLang);
 
@@ -104,6 +103,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 			const res = await this.httpRequestService.send(endpoint, {
 				method: 'POST',
 				headers: {
+					'Authorization': `DeepL-Auth-Key ${this.serverSettings.deeplAuthKey}`,
 					'Content-Type': 'application/x-www-form-urlencoded',
 					Accept: 'application/json, */*',
 				},