diff --git a/src/main/java/com/sb/web/auth/domain/Member.java b/src/main/java/com/sb/web/auth/domain/Member.java
index d193699..5a671c4 100644
--- a/src/main/java/com/sb/web/auth/domain/Member.java
+++ b/src/main/java/com/sb/web/auth/domain/Member.java
@@ -23,8 +23,9 @@ public class Member implements Serializable {
     private String password;     // BCrypt 해시 (소셜 전용은 null)
     private String name;
     private String email;
-    private String provider;     // LOCAL / NAVER
+    private String provider;     // LOCAL / NAVER / GOOGLE
     private String providerId;   // 소셜 제공자 측 고유 ID
+    private String googleId;     // 구글 sub (계정 연결용 — LOCAL 계정에 구글을 연결해도 provider 는 유지)
     private String role;         // USER / ADMIN
     private String status;       // ACTIVE / SUSPENDED / WITHDRAWN
     private LocalDateTime createdAt;
diff --git a/src/main/java/com/sb/web/auth/mapper/MemberMapper.java b/src/main/java/com/sb/web/auth/mapper/MemberMapper.java
index df2550c..f1c72f2 100644
--- a/src/main/java/com/sb/web/auth/mapper/MemberMapper.java
+++ b/src/main/java/com/sb/web/auth/mapper/MemberMapper.java
@@ -22,6 +22,15 @@ public interface MemberMapper {
     Member findByProvider(@Param("provider") String provider,
                           @Param("providerId") String providerId);
 
+    /** 구글 sub 로 회원 조회 (연결된 LOCAL 계정 + 순수 구글 계정 모두). */
+    Member findByGoogleId(@Param("googleId") String googleId);
+
+    /** 구글 로그인 시 연결 대상이 될 같은 이메일의 기존 계정(LOCAL 우선, 미연결만). */
+    Member findByEmailForLink(@Param("email") String email);
+
+    /** 기존 계정에 구글 sub 연결 (provider 유지). */
+    int linkGoogle(@Param("id") Long id, @Param("googleId") String googleId);
+
     int countByLoginId(@Param("loginId") String loginId);
 
     int insert(Member member);
diff --git a/src/main/java/com/sb/web/auth/service/AuthService.java b/src/main/java/com/sb/web/auth/service/AuthService.java
index cf3ef51..2bc7b6e 100644
--- a/src/main/java/com/sb/web/auth/service/AuthService.java
+++ b/src/main/java/com/sb/web/auth/service/AuthService.java
@@ -183,12 +183,30 @@ public class AuthService {
         }
         String sub = String.valueOf(info.get("sub"));
         String email = info.get("email") == null ? null : String.valueOf(info.get("email"));
+        boolean emailVerified = "true".equals(String.valueOf(info.get("email_verified")));
         String name = info.get("name") != null ? String.valueOf(info.get("name"))
                 : (email != null ? email.split("@")[0] : "사용자");
 
-        Member member = memberMapper.findByProvider("GOOGLE", sub);
+        // 1) 구글 sub 로 이미 연결/가입된 계정 조회
+        Member member = memberMapper.findByGoogleId(sub);
+
+        // 2) 없으면 같은 (검증된)이메일의 기존 계정에 구글 연결 — 중복 계정/데이터 분리 방지
+        if (member == null && email != null && !email.isBlank() && emailVerified) {
+            Member existing = memberMapper.findByEmailForLink(email);
+            if (existing != null) {
+                if (!"ACTIVE".equals(existing.getStatus())) {
+                    throw new ApiException(HttpStatus.FORBIDDEN, "사용할 수 없는 계정입니다.");
+                }
+                memberMapper.linkGoogle(existing.getId(), sub);
+                existing.setGoogleId(sub);
+                member = existing;
+                log.info("[google] linked to existing member id={} provider={} email={}",
+                        member.getId(), member.getProvider(), email);
+            }
+        }
+
+        // 3) 그래도 없으면 신규 구글 계정 생성(최초 로그인 = 가입). 가입 제한 시 차단.
         if (member == null) {
-            // 최초 로그인 = 가입. 가입 제한 시 차단.
             if (!appSettingService.isSignupEnabled()) {
                 throw new ApiException(HttpStatus.FORBIDDEN, "현재 회원가입이 제한되어 있습니다.");
             }
@@ -197,6 +215,7 @@ public class AuthService {
                     .email(email)
                     .provider("GOOGLE")
                     .providerId(sub)
+                    .googleId(sub)
                     .role("USER")
                     .status("ACTIVE")
                     .build();
diff --git a/src/main/resources/db/member.sql b/src/main/resources/db/member.sql
index 6a32d76..56a9184 100644
--- a/src/main/resources/db/member.sql
+++ b/src/main/resources/db/member.sql
@@ -20,6 +20,13 @@ CREATE TABLE IF NOT EXISTS member (
     UNIQUE KEY uk_member_provider (provider, provider_id)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
+-- 구글 계정 연결: 기존 LOCAL 계정에 구글 sub 를 연결해 같은 이메일이면 한 계정으로 통합한다.
+-- (provider 는 LOCAL 로 유지 → 아이디/비밀번호 로그인·프로필 편집 그대로) MariaDB IF NOT EXISTS 로 멱등.
+ALTER TABLE member ADD COLUMN IF NOT EXISTS google_id VARCHAR(100) NULL COMMENT '구글 sub (계정 연결용)' AFTER provider_id;
+ALTER TABLE member ADD UNIQUE KEY IF NOT EXISTS uk_member_google_id (google_id);
+-- 기존 구글 계정(provider=GOOGLE)의 sub 를 google_id 로 백필(멱등 — 이미 채워졌으면 아무 것도 안 함).
+UPDATE member SET google_id = provider_id WHERE provider = 'GOOGLE' AND google_id IS NULL AND provider_id IS NOT NULL;
+
 -- ============================================================
 -- 앱 전역 설정 (단일 행, id=1). 관리자 화면에서 변경.
 -- ============================================================
diff --git a/src/main/resources/mapper/MemberMapper.xml b/src/main/resources/mapper/MemberMapper.xml
index 7ed95a1..fd7d92b 100644
--- a/src/main/resources/mapper/MemberMapper.xml
+++ b/src/main/resources/mapper/MemberMapper.xml
@@ -11,6 +11,7 @@
         <result property="email" column="email"/>
         <result property="provider" column="provider"/>
         <result property="providerId" column="provider_id"/>
+        <result property="googleId" column="google_id"/>
         <result property="role" column="role"/>
         <result property="status" column="status"/>
         <result property="createdAt" column="created_at"/>
@@ -18,7 +19,7 @@
     </resultMap>
 
     <sql id="columns">
-        id, login_id, password, name, email, provider, provider_id, role, status, created_at, updated_at
+        id, login_id, password, name, email, provider, provider_id, google_id, role, status, created_at, updated_at
     </sql>
 
     <select id="findById" parameterType="long" resultMap="memberResultMap">
@@ -39,15 +40,34 @@
         WHERE provider = #{provider} AND provider_id = #{providerId}
     </select>
 
+    <!-- 구글 sub 로 회원 조회 (연결된 LOCAL 계정 + 순수 구글 계정 모두 google_id 로 찾음) -->
+    <select id="findByGoogleId" parameterType="string" resultMap="memberResultMap">
+        SELECT <include refid="columns"/> FROM member WHERE google_id = #{googleId}
+    </select>
+
+    <!-- 구글 로그인 시 같은 이메일의 기존 계정 1건(연결 대상). LOCAL 계정 우선. -->
+    <select id="findByEmailForLink" parameterType="string" resultMap="memberResultMap">
+        SELECT <include refid="columns"/>
+        FROM member
+        WHERE email = #{email} AND status = 'ACTIVE' AND google_id IS NULL
+        ORDER BY (provider = 'LOCAL') DESC, id ASC
+        LIMIT 1
+    </select>
+
+    <!-- 기존 계정에 구글 연결 (provider 는 그대로 유지) -->
+    <update id="linkGoogle">
+        UPDATE member SET google_id = #{googleId}, updated_at = NOW() WHERE id = #{id}
+    </update>
+
     <select id="countByLoginId" parameterType="string" resultType="int">
         SELECT COUNT(*) FROM member WHERE login_id = #{loginId}
     </select>
 
     <insert id="insert" parameterType="com.sb.web.auth.domain.Member"
             useGeneratedKeys="true" keyProperty="id">
-        INSERT INTO member (login_id, password, name, email, provider, provider_id, role, status, created_at, updated_at)
+        INSERT INTO member (login_id, password, name, email, provider, provider_id, google_id, role, status, created_at, updated_at)
         VALUES (#{loginId}, #{password}, #{name}, #{email},
-                #{provider}, #{providerId}, #{role}, #{status}, NOW(), NOW())
+                #{provider}, #{providerId}, #{googleId}, #{role}, #{status}, NOW(), NOW())
     </insert>
 
     <update id="updatePassword">