diff --git a/src/main/java/com/example/solidconnection/auth/dto/oauth/OAuthSignInResponse.java b/src/main/java/com/example/solidconnection/auth/dto/oauth/OAuthSignInResponse.java
index 9e9f75851..daa42d497 100644
--- a/src/main/java/com/example/solidconnection/auth/dto/oauth/OAuthSignInResponse.java
+++ b/src/main/java/com/example/solidconnection/auth/dto/oauth/OAuthSignInResponse.java
@@ -3,9 +3,10 @@
 import com.example.solidconnection.auth.dto.SignInResult;
 
 public record OAuthSignInResponse(
+        boolean isRegistered,
         String accessToken) implements OAuthResponse {
 
     public static OAuthSignInResponse from(SignInResult signInResult) {
-        return new OAuthSignInResponse(signInResult.accessToken());
+        return new OAuthSignInResponse(true, signInResult.accessToken());
     }
 }
diff --git a/src/main/java/com/example/solidconnection/auth/dto/oauth/SignUpPrepareResponse.java b/src/main/java/com/example/solidconnection/auth/dto/oauth/SignUpPrepareResponse.java
index 663b8906a..5a6c60c57 100644
--- a/src/main/java/com/example/solidconnection/auth/dto/oauth/SignUpPrepareResponse.java
+++ b/src/main/java/com/example/solidconnection/auth/dto/oauth/SignUpPrepareResponse.java
@@ -1,6 +1,7 @@
 package com.example.solidconnection.auth.dto.oauth;
 
 public record SignUpPrepareResponse(
+        boolean isRegistered,
         String nickname,
         String email,
         String profileImageUrl,
@@ -8,6 +9,7 @@ public record SignUpPrepareResponse(
 
     public static SignUpPrepareResponse of(OAuthUserInfoDto oAuthUserInfoDto, String signUpToken) {
         return new SignUpPrepareResponse(
+                false,
                 oAuthUserInfoDto.getNickname(),
                 oAuthUserInfoDto.getEmail(),
                 oAuthUserInfoDto.getProfileImageUrl(),
diff --git a/src/test/java/com/example/solidconnection/auth/service/oauth/OAuthServiceTest.java b/src/test/java/com/example/solidconnection/auth/service/oauth/OAuthServiceTest.java
index 49d11a340..2dd430fba 100644
--- a/src/test/java/com/example/solidconnection/auth/service/oauth/OAuthServiceTest.java
+++ b/src/test/java/com/example/solidconnection/auth/service/oauth/OAuthServiceTest.java
@@ -65,6 +65,7 @@ void setUp() { // 실제 client 호출하지 않도록 mocking
         assertThat(response).isInstanceOf(OAuthSignInResponse.class);
         OAuthSignInResponse signInResponse = (OAuthSignInResponse) response;
         assertAll(
+                () -> assertThat(signInResponse.isRegistered()).isTrue(),
                 () -> assertThat(signInResponse.accessToken()).isNotBlank(),
                 () -> assertThat(oAuthResult.refreshToken()).isNotBlank()
         );
@@ -80,6 +81,7 @@ void setUp() { // 실제 client 호출하지 않도록 mocking
         assertThat(response).isInstanceOf(SignUpPrepareResponse.class);
         SignUpPrepareResponse signUpPrepareResponse = (SignUpPrepareResponse) response;
         assertAll(
+                () -> assertThat(signUpPrepareResponse.isRegistered()).isFalse(),
                 () -> assertThat(signUpPrepareResponse.signUpToken()).isNotBlank(),
                 () -> assertThat(signUpPrepareResponse.email()).isEqualTo(email),
                 () -> assertThat(signUpPrepareResponse.profileImageUrl()).isEqualTo(profileImageUrl),