diff --git a/src/main/java/com/example/team4backend/controller/AiController.java b/src/main/java/com/example/team4backend/controller/AiController.java
index bc28c55..d07c90e 100644
--- a/src/main/java/com/example/team4backend/controller/AiController.java
+++ b/src/main/java/com/example/team4backend/controller/AiController.java
@@ -22,6 +22,7 @@ public ResponseEntity<ApiResult<Void>> chat(@RequestBody PromptRequest promptReq
         System.out.println("=== AiController.chat() 호출됨 === userInput: " + promptRequest.getUserInput());
         String aiResponse = aiService.generateContent(promptRequest.getUserInput());
         System.out.println("=== AiController.chat() 응답 완료 ===");
+
         return ResponseEntity.ok(ApiResult.ok(aiResponse));
     }
 }
diff --git a/src/main/java/com/example/team4backend/controller/TargetController.java b/src/main/java/com/example/team4backend/controller/TargetController.java
index d4b66c9..0b5b3cc 100644
--- a/src/main/java/com/example/team4backend/controller/TargetController.java
+++ b/src/main/java/com/example/team4backend/controller/TargetController.java
@@ -73,4 +73,14 @@ public ResponseEntity<ApiResult<Void>> deleteTarget(
         targetService.deleteTarget(userDetails.getId(), targetId);
         return ResponseEntity.ok(ApiResult.ok("대상자 정보가 삭제되었습니다."));
     }
+
+    @Operation(summary = "최근 메시지 보낸날짜 갱신", description = "메시지를 보내면 최근 메시지를 보낸 날짜를 갱신합니다.")
+    @PutMapping("/{targetId}/message-date")
+    public ResponseEntity<ApiResult<Void>> updateLastMessageDate(
+            @AuthenticationPrincipal CustomUserDetails userDetails,
+            @PathVariable Long targetId
+    ) {
+        targetService.updateLastMessageDate(userDetails.getId(), targetId);
+        return ResponseEntity.ok(ApiResult.ok("최근 메시지 보낸 날짜가 업데이트되었습니다."));
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/com/example/team4backend/domain/TargetPerson.java b/src/main/java/com/example/team4backend/domain/TargetPerson.java
index bbeb593..53278ab 100644
--- a/src/main/java/com/example/team4backend/domain/TargetPerson.java
+++ b/src/main/java/com/example/team4backend/domain/TargetPerson.java
@@ -47,6 +47,8 @@ public class TargetPerson extends BaseTimeEntity {
     @JoinColumn(name = "chat_style_id")
     private ChatStyle chatStyle;
 
+    private Instant lastMessageDate;
+
     private Instant deletedAt;
 
     @Builder
diff --git a/src/main/java/com/example/team4backend/repository/TargetPersonRepository.java b/src/main/java/com/example/team4backend/repository/TargetPersonRepository.java
index a86891e..1a1421f 100644
--- a/src/main/java/com/example/team4backend/repository/TargetPersonRepository.java
+++ b/src/main/java/com/example/team4backend/repository/TargetPersonRepository.java
@@ -6,6 +6,7 @@
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
+import java.time.Instant;
 import java.util.Optional;
 import java.util.List;
 
@@ -30,4 +31,10 @@ public interface TargetPersonRepository extends JpaRepository<TargetPerson, Long
 
     @Query("SELECT t.user.id FROM TargetPerson t WHERE t.id = :id AND t.deletedAt IS NULL")
     Optional<Long> findOwnerIdByIdAndDeletedAtIsNull(@Param("id") Long id);
+
+    @Modifying
+    @Query("UPDATE TargetPerson t SET t.lastMessageDate = :date WHERE t.id = :targetId AND t.user.id = :userId AND t.deletedAt IS NULL")
+    int updateLastMessageDate(@Param("targetId") Long targetId,
+                              @Param("userId") Long userId,
+                              @Param("date") Instant date);
 }
diff --git a/src/main/java/com/example/team4backend/security/SecurityPaths.java b/src/main/java/com/example/team4backend/security/SecurityPaths.java
index 7385a98..1d8d2aa 100644
--- a/src/main/java/com/example/team4backend/security/SecurityPaths.java
+++ b/src/main/java/com/example/team4backend/security/SecurityPaths.java
@@ -12,8 +12,7 @@ private SecurityPaths() {}
             "/prompts",
             "/relationships",
             "/chat-styles",
-            "/health",
-            "/"
+            "/health"
     };
 
     public static final String[] CSRF_IGNORED = {
@@ -28,7 +27,8 @@ private SecurityPaths() {}
             "/prompts",
             "/users",
             "/targets",
-            "/relationships"
+            "/relationships",
+            "/health"
     };
 
     public static final String[] PUBLIC_DOCS = {
diff --git a/src/main/java/com/example/team4backend/service/TargetService.java b/src/main/java/com/example/team4backend/service/TargetService.java
index 2576080..c577cca 100644
--- a/src/main/java/com/example/team4backend/service/TargetService.java
+++ b/src/main/java/com/example/team4backend/service/TargetService.java
@@ -19,6 +19,7 @@
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.time.Instant;
 import java.util.List;
 
 @Service
@@ -150,4 +151,18 @@ public void deleteTarget(Long userId, Long targetId) {
 
         throw new BusinessException(ErrorCode.AUTH_FORBIDDEN);
     }
+
+    @Transactional
+    public void updateLastMessageDate(Long userId, Long targetId) {
+        int updated = targetPersonRepository.updateLastMessageDate(
+                targetId,
+                userId,
+                Instant.now()
+        );
+
+        if (updated == 0) {
+            // targetId가 존재하지 않거나 userId가 일치하지 않음
+            throw new BusinessException(ErrorCode.NOT_FOUND);
+        }
+    }
 }