diff --git a/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberApi.java b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberApi.java
index 9fd73ee..a13b436 100644
--- a/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberApi.java
+++ b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberApi.java
@@ -3,6 +3,7 @@
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import kr.ac.kookmin.stream.api.app.AppApiUser;
+import kr.ac.kookmin.stream.api.app.core.member.request.FcmTokenUpdateRequest;
 import kr.ac.kookmin.stream.api.app.core.member.request.MemberSignUpRequest;
 import kr.ac.kookmin.stream.api.common.dto.ApiResponse;
 import kr.ac.kookmin.stream.api.common.openapi.ApiErrorCode;
@@ -12,7 +13,7 @@
 /**
  * 학생 앱 회원 API의 문서 명세. 구현은 {@link AppMemberController}가 맡는다.
  */
-@Tag(name = "회원", description = "학생 앱 회원가입")
+@Tag(name = "회원", description = "학생 앱 회원가입·FCM 토큰 등록")
 public interface AppMemberApi {
 
     /** 회원가입. 로그인 응답의 signUpRequired가 true인 회원이 전화번호와 약관 동의 여부를 등록한다. */
@@ -28,4 +29,13 @@ public interface AppMemberApi {
         "PHONE_NUMBER_ALREADY_EXISTS"
     })
     ApiResponse<Void> signUp(AppApiUser apiUser, MemberSignUpRequest request);
+
+    /** FCM 토큰 등록. 앱이 Firebase에서 받은 등록 토큰을 로그인한 회원에게 저장한다. */
+    @Operation(summary = "FCM 토큰 등록",
+        description = """
+            로그인한 회원의 FCM 등록 토큰을 저장한다. 로그인 직후와 토큰이 갱신될 때(onTokenRefresh) 호출한다.
+            같은 토큰을 가진 다른 회원이 있으면 그 회원의 토큰은 지운다(한 기기에서 계정을 바꾼 경우).""")
+    @ApiErrorCode(type = CommonErrorCode.class, codes = {"INVALID_INPUT"})
+    @ApiErrorCode(type = MemberErrorCode.class, codes = {"MEMBER_NOT_FOUND"})
+    ApiResponse<Void> updateFcmToken(AppApiUser apiUser, FcmTokenUpdateRequest request);
 }
diff --git a/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberController.java b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberController.java
index b40c3a9..67d0ae9 100644
--- a/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberController.java
+++ b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/AppMemberController.java
@@ -2,10 +2,12 @@
 
 import jakarta.validation.Valid;
 import kr.ac.kookmin.stream.api.app.AppApiUser;
+import kr.ac.kookmin.stream.api.app.core.member.request.FcmTokenUpdateRequest;
 import kr.ac.kookmin.stream.api.app.core.member.request.MemberSignUpRequest;
 import kr.ac.kookmin.stream.api.common.dto.ApiResponse;
 import kr.ac.kookmin.stream.member.domain.member.service.MemberService;
 import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.PatchMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -27,4 +29,14 @@ public ApiResponse<Void> signUp(
         memberService.signUp(apiUser.userId(), request.toCommand());
         return ApiResponse.success();
     }
+
+    @Override
+    @PatchMapping("/me/fcm-token")
+    public ApiResponse<Void> updateFcmToken(
+        AppApiUser apiUser,
+        @Valid @RequestBody FcmTokenUpdateRequest request
+    ) {
+        memberService.updateFcmToken(apiUser.userId(), request.fcmToken());
+        return ApiResponse.success();
+    }
 }
diff --git a/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/request/FcmTokenUpdateRequest.java b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/request/FcmTokenUpdateRequest.java
new file mode 100644
index 0000000..c305a2f
--- /dev/null
+++ b/api/app-api/src/main/java/kr/ac/kookmin/stream/api/app/core/member/request/FcmTokenUpdateRequest.java
@@ -0,0 +1,13 @@
+package kr.ac.kookmin.stream.api.app.core.member.request;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Pattern;
+import jakarta.validation.constraints.Size;
+
+public record FcmTokenUpdateRequest(
+    // FCM 등록 토큰({인스턴스 ID}:APA91b...)과 FID 모두 base64url 문자와 ':'만 쓴다. 길이는 members.fcm_token 컬럼에 맞춘다
+    @NotBlank(message = "FCM 토큰을 입력해 주세요.")
+    @Size(max = 255, message = "FCM 토큰은 255자 이하여야 합니다.")
+    @Pattern(regexp = "^[A-Za-z0-9_:-]+$", message = "FCM 토큰 형식이 올바르지 않습니다.")
+    String fcmToken
+) {}
diff --git a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/domain/Member.java b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/domain/Member.java
index b273e03..158bc59 100644
--- a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/domain/Member.java
+++ b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/domain/Member.java
@@ -67,4 +67,13 @@ public void registerPhoneNumber(String phoneNumber) {
     public boolean hasPhoneNumber() {
         return phoneNumber != null;
     }
+
+    // 앱이 Firebase에서 받은 등록 토큰으로 바꾼다. 바뀐 값이 있으면 true를 돌려준다
+    public boolean updateFcmToken(String fcmToken) {
+        if (Objects.equals(this.fcmToken, fcmToken)) {
+            return false;
+        }
+        this.fcmToken = fcmToken;
+        return true;
+    }
 }
diff --git a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/repository/MemberRepository.java b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/repository/MemberRepository.java
index d2e74f8..bd0465e 100644
--- a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/repository/MemberRepository.java
+++ b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/repository/MemberRepository.java
@@ -11,4 +11,5 @@ public interface MemberRepository {
     List<Member> findAllByIds(List<Long> ids);
     List<Long> searchIdsByKeyword(String keyword);
     Member save(Member member);
+    void clearFcmTokenOfOthers(Long memberId, String fcmToken);
 }
diff --git a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/MemberService.java b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/MemberService.java
index 0c584bc..39d1a0f 100644
--- a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/MemberService.java
+++ b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/MemberService.java
@@ -15,4 +15,5 @@ public interface MemberService {
     Member registerOrUpdateByStudentId(MemberProfileCommand command);
     Member signUp(Long memberId, MemberSignUpCommand command);
     boolean isSignedUp(Long memberId);
+    void updateFcmToken(Long memberId, String fcmToken);
 }
diff --git a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/impl/MemberServiceImpl.java b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/impl/MemberServiceImpl.java
index a8ad7c3..f6bdf2d 100644
--- a/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/impl/MemberServiceImpl.java
+++ b/core/domain/member/src/main/java/kr/ac/kookmin/stream/member/domain/member/service/impl/MemberServiceImpl.java
@@ -83,6 +83,18 @@ public boolean isSignedUp(Long memberId) {
         return isSignedUp(getById(memberId));
     }
 
+    // 한 기기를 다른 계정으로 쓰게 되면 이전 회원의 알림이 새 사용자에게 가지 않도록, 다른 회원에게 남은 같은 토큰을 지운다.
+    // 이미 중복이 들어 있는 데이터도 정리하려고 자기 토큰이 그대로여도 매번 지운다
+    @Override
+    @Transactional
+    public void updateFcmToken(Long memberId, String fcmToken) {
+        Member member = getById(memberId);
+        memberRepository.clearFcmTokenOfOthers(memberId, fcmToken);
+        if (member.updateFcmToken(fcmToken)) {
+            memberRepository.save(member);
+        }
+    }
+
     // 전화번호와 필수 약관 동의가 모두 있어야 가입을 마친 것으로 본다
     private boolean isSignedUp(Member member) {
         return member.hasPhoneNumber() && memberTermService.hasAgreedRequiredTerms(member.getId());
diff --git a/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberJpaRepository.java b/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberJpaRepository.java
index a1b224b..0fd828a 100644
--- a/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberJpaRepository.java
+++ b/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberJpaRepository.java
@@ -3,6 +3,7 @@
 import java.util.List;
 import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
@@ -22,4 +23,14 @@ public interface MemberJpaRepository extends JpaRepository<MemberJpaEntity, Long
         AND (m.name LIKE CONCAT('%', :keyword, '%') OR m.studentId LIKE CONCAT('%', :keyword, '%'))
         """)
     List<Long> searchIdsByKeyword(@Param("keyword") String keyword);
+
+    // 탈퇴 회원에게는 어차피 보내지 않으므로 is_deleted와 관계없이 지운다
+    @Modifying(clearAutomatically = true)
+    @Query("""
+        UPDATE MemberJpaEntity m
+        SET m.fcmToken = NULL
+        WHERE m.fcmToken = :fcmToken
+        AND m.id <> :memberId
+        """)
+    void clearFcmTokenOfOthers(@Param("memberId") Long memberId, @Param("fcmToken") String fcmToken);
 }
diff --git a/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberRepositoryImpl.java b/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberRepositoryImpl.java
index 9996c87..0dba47a 100644
--- a/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberRepositoryImpl.java
+++ b/infrastructure/db/src/main/java/kr/ac/kookmin/stream/db/member/MemberRepositoryImpl.java
@@ -61,4 +61,9 @@ public Member save(Member member) {
             throw e;
         }
     }
+
+    @Override
+    public void clearFcmTokenOfOthers(Long memberId, String fcmToken) {
+        memberJpaRepository.clearFcmTokenOfOthers(memberId, fcmToken);
+    }
 }