diff --git a/src/main/java/com/petlog/docs/PetGroupControllerDocs.java b/src/main/java/com/petlog/docs/PetGroupControllerDocs.java
index 17aeebe..3057d79 100644
--- a/src/main/java/com/petlog/docs/PetGroupControllerDocs.java
+++ b/src/main/java/com/petlog/docs/PetGroupControllerDocs.java
@@ -43,5 +43,5 @@ public interface PetGroupControllerDocs {
 
     @io.swagger.v3.oas.annotations.responses.ApiResponse(responseCode = "200", description = "참고사항 수정에 성공하였습니다.")
     @Operation(summary = "참고사항 수정 API")
-    ResponseEntity<ApiResponse<Void>> updateNote(@PathVariable final Long groupId, @RequestBody final UpdateNoteRequestDto request);
+    ResponseEntity<ApiResponse<Void>> updateNote(@Authenticated final Long memberId, @PathVariable final Long groupId, @RequestBody final UpdateNoteRequestDto request);
 }
diff --git a/src/main/java/com/petlog/petgroup/controller/PetGroupController.java b/src/main/java/com/petlog/petgroup/controller/PetGroupController.java
index a1f36ce..4c4bcbd 100644
--- a/src/main/java/com/petlog/petgroup/controller/PetGroupController.java
+++ b/src/main/java/com/petlog/petgroup/controller/PetGroupController.java
@@ -94,7 +94,7 @@ public ResponseEntity<ApiResponse<GetJoinCodeResponseDto>> getJoinCode(
         @Authenticated final Long memberId,
         @PathVariable final Long groupId
     ) {
-        final GetJoinCodeDto dto = petGroupService.getPetGroupJoinCode(memberId, groupId);
+        final GetJoinCodeDto dto = petGroupService.getJoinCode(memberId, groupId);
         final GetJoinCodeResponseDto response = new GetJoinCodeResponseDto(dto.joinCode());
 
         return ResponseEntity.ok(
@@ -117,9 +117,12 @@ public ResponseEntity<ApiResponse<GetNoteResponseDto>> getNote(
 
     @PatchMapping("/{groupId}/note")
     public ResponseEntity<ApiResponse<Void>> updateNote(
+        @Authenticated final Long memberId,
         @PathVariable final Long groupId,
         @RequestBody final UpdateNoteRequestDto request
     ) {
+        petGroupService.updateNote(memberId, groupId, request.note());
+
         return ResponseEntity.ok(
             ApiResponse.success(UPDATE_NOTE)
         );
diff --git a/src/main/java/com/petlog/petgroup/entity/PetGroup.java b/src/main/java/com/petlog/petgroup/entity/PetGroup.java
index 2fecdd0..93884d0 100644
--- a/src/main/java/com/petlog/petgroup/entity/PetGroup.java
+++ b/src/main/java/com/petlog/petgroup/entity/PetGroup.java
@@ -34,4 +34,8 @@ public PetGroup(
         this.joinCode = joinCode;
         this.note = note;
     }
+
+    public void updateNote(final String note) {
+        this.note = note;
+    }
 }
diff --git a/src/main/java/com/petlog/petgroup/repository/PetGroupMemberRepository.java b/src/main/java/com/petlog/petgroup/repository/PetGroupMemberRepository.java
index 39ea48a..efaa19f 100644
--- a/src/main/java/com/petlog/petgroup/repository/PetGroupMemberRepository.java
+++ b/src/main/java/com/petlog/petgroup/repository/PetGroupMemberRepository.java
@@ -8,6 +8,7 @@
 import org.springframework.data.jpa.repository.Query;
 
 import java.util.List;
+import java.util.Optional;
 
 public interface PetGroupMemberRepository extends JpaRepository<PetGroupMember, Long> {
 
@@ -27,4 +28,6 @@ public interface PetGroupMemberRepository extends JpaRepository<PetGroupMember,
     void deleteByMemberIdAndGroupId(final Long memberId, final Long groupId);
 
     boolean existsByMemberAndPetGroup(final Member member, final PetGroup group);
+
+    Optional<PetGroupMember> findByMemberAndPetGroup(final Member member, final PetGroup group);
 }
diff --git a/src/main/java/com/petlog/petgroup/service/PetGroupService.java b/src/main/java/com/petlog/petgroup/service/PetGroupService.java
index 1a9134b..572fc02 100644
--- a/src/main/java/com/petlog/petgroup/service/PetGroupService.java
+++ b/src/main/java/com/petlog/petgroup/service/PetGroupService.java
@@ -131,7 +131,7 @@ private void validateMemberInPetGroup(final Member member, final PetGroup petGro
     }
 
     @Transactional(readOnly = true)
-    public GetJoinCodeDto getPetGroupJoinCode(final Long memberId, final Long groupId) {
+    public GetJoinCodeDto getJoinCode(final Long memberId, final Long groupId) {
         final Member member = getMember(memberId);
         final PetGroup petGroup = getPetGroup(groupId);
         validateMemberInPetGroup(member, petGroup);
@@ -147,4 +147,26 @@ public GetNoteDto getNote(final Long memberId, final Long groupId) {
 
         return new GetNoteDto(petGroup.getNote());
     }
+
+    @Transactional
+    public void updateNote(final Long memberId, final Long groupId, final String note) {
+        final Member member = getMember(memberId);
+        final PetGroup petGroup = getPetGroup(groupId);
+        final PetGroupMember petGroupMember = getPetGroupMember(member, petGroup);
+
+        validateMemberIsGroupOwner(petGroupMember);
+
+        petGroup.updateNote(note);
+    }
+
+    private PetGroupMember getPetGroupMember(final Member member, final PetGroup petGroup) {
+        return petGroupMemberRepository.findByMemberAndPetGroup(member, petGroup)
+            .orElseThrow(() -> new IllegalArgumentException("그룹에 존재하지 않는 회원입니다."));
+    }
+
+    private void validateMemberIsGroupOwner(final PetGroupMember petGroupMember) {
+        if(!petGroupMember.isGroupOwner()) {
+            throw new IllegalArgumentException("참고사항 수정은 그룹장만 할 수 있습니다.");
+        }
+    }
 }