diff --git a/components/Timetable.tsx b/components/Timetable.tsx
index 57ff86c..e3024c6 100644
--- a/components/Timetable.tsx
+++ b/components/Timetable.tsx
@@ -29,7 +29,7 @@ const Timetable = ({ user }) => {
       if (input.checked) {
         alert("Error: Conflict select");
         location.reload();
-        return
+        return;
       }
     }
     for (const input of conflicts[target.name]) {
@@ -149,7 +149,15 @@ const Timetable = ({ user }) => {
       } else {
         indexToElement[index].style.display = "";
       }
-      indexToElement[index].checked = myselect.includes(index);
+      const includes = myselect.includes(index);
+      indexToElement[index].checked = includes;
+      // after checked, find conflicts input
+      if (includes) {
+        for (const input of conflicts[index]) {
+          console.log("conflict", input);
+          input.setAttribute("disabled", "true");
+        }
+      }
     }
   };
   React.useEffect(() => {