diff --git a/app/gateway-api/src/auth/kakaoAccountVerification.ts b/app/gateway-api/src/auth/kakaoAccountVerification.ts
index 89eb4bdb..e53c8524 100644
--- a/app/gateway-api/src/auth/kakaoAccountVerification.ts
+++ b/app/gateway-api/src/auth/kakaoAccountVerification.ts
@@ -2,6 +2,8 @@ import { randomInt } from 'node:crypto';
 
 import { addDays, addSeconds, isAfter, isValid, parseISO } from 'date-fns';
 
+import { formatServerDateTime } from '@sammo-ts/common/time/ServerDateTime';
+
 import type { KakaoOAuthClient, KakaoOAuthToken, KakaoUserInfo } from './kakaoClient.js';
 import type { OAuthSessionStore } from './oauthSessionStore.js';
 import type { UserOAuthInfo, UserRecord, UserRepository } from './userRepository.js';
@@ -221,7 +223,7 @@ export const requireKakaoTalkProof = async (options: {
     try {
         await options.kakaoClient.sendTalkMessage(
             options.accessToken,
-            `인증 코드는 ${challenge.code} 입니다. ${challenge.expiresAt} 이내에 입력해 주세요.`,
+            `인증 코드는 ${challenge.code} 입니다. ${formatServerDateTime(challenge.expiresAt)} (한국 시간) 이내에 입력해 주세요.`,
             options.publicBaseUrl
         );
     } catch (error) {
@@ -253,7 +255,7 @@ export const verifyKakaoTalkChallenge = async (options: {
     if (result.status === 'locked') {
         throw new KakaoVerificationError(
             'IDENTITY_MISMATCH',
-            `인증 실패 횟수를 초과했습니다. ${result.expiresAt}까지 기다려 주세요.`
+            `인증 실패 횟수를 초과했습니다. ${formatServerDateTime(result.expiresAt)} (한국 시간)까지 기다려 주세요.`
         );
     }
     if (result.status === 'mismatch') {
diff --git a/app/gateway-api/test/authFlow.test.ts b/app/gateway-api/test/authFlow.test.ts
index db8ead30..de7195c6 100644
--- a/app/gateway-api/test/authFlow.test.ts
+++ b/app/gateway-api/test/authFlow.test.ts
@@ -14,6 +14,7 @@ import { InMemoryProfileStatusService } from '../src/lobby/profileStatusService.
 import { appRouter } from '../src/router.js';
 import type { GatewayPrismaClient } from '@sammo-ts/infra';
 import { decryptGameSessionToken, type UserSanctions } from '@sammo-ts/common/auth/gameToken';
+import { formatServerDateTime } from '@sammo-ts/common/time/ServerDateTime';
 import { createPasswordEnvelopeService } from '../src/auth/passwordEnvelope.js';
 import type { GatewayProfileRepository } from '../src/orchestrator/profileRepository.js';
 
@@ -987,6 +988,9 @@ describe('gateway auth flow', () => {
         });
         const code = sentTalkMessages[0]?.match(/인증 코드는 (\d{4})/)?.[1];
         expect(code).toBeTruthy();
+        expect(sentTalkMessages[0]).toBe(
+            `인증 코드는 ${code} 입니다. ${formatServerDateTime(login.expiresAt)} (한국 시간) 이내에 입력해 주세요.`
+        );
         const completed = await caller.auth.kakaoOtp({ challengeId: login.challengeId, code: code! });
         expect(completed.validUntil).toBeTruthy();
         expect((await users.findById(user.id))?.kakaoTalkVerifiedUntil).toBe(completed.validUntil);