diff --git a/src/main/java/org/ntlab/tampoposerver/models/Activity.java b/src/main/java/org/ntlab/tampoposerver/models/Activity.java
index bd2781f..de9d1bf 100644
--- a/src/main/java/org/ntlab/tampoposerver/models/Activity.java
+++ b/src/main/java/org/ntlab/tampoposerver/models/Activity.java
@@ -3,12 +3,21 @@
 import com.fasterxml.jackson.annotation.JsonIdentityInfo;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+import com.fasterxml.jackson.annotation.JsonFormat;
+
+import java.time.LocalDateTime;
+
 public class Activity {
-    @JsonIgnore
+
     private String userId;
     private String activityId;
     private String text;
-    private String updateTime;
+
+    @JsonFormat(pattern = "yyyy/MM/dd HH:mm")
+    private LocalDateTime updateTime;
 
     public String getUserId() {
         return userId;
@@ -26,11 +35,11 @@
         this.text = text;
     }
 
-    public String getUpdateTime() {
+    public LocalDateTime getUpdateTime() {
         return updateTime;
     }
 
-    public void setUpdateTime(String updateTime) {
+    public void setUpdateTime(LocalDateTime updateTime) {
         this.updateTime = updateTime;
     }
 
@@ -42,10 +51,10 @@
         this.activityId = activityId;
     }
 
-    public Activity(String u, String a, String t, String ut){
+    public Activity(String u, String a, String t) {
         userId = u;
         activityId = a;
         text = t;
-        updateTime = ut;
+        updateTime = LocalDateTime.now();
     }
 }