diff --git a/modules/contest.js b/modules/contest.js
index ca1beed..2ef4439 100644
--- a/modules/contest.js
+++ b/modules/contest.js
@@ -89,6 +89,9 @@ app.post('/contest/:id/edit', async (req, res) => {
       let ranklist = await ContestRanklist.create();
       await ranklist.save();
       contest.ranklist_id = ranklist.id;
+
+      // Only new contest can be set type
+      contest.type = req.body.type;
     }
 
     if (!req.body.title.trim()) throw new ErrorMessage('比赛名不能为空。');
@@ -97,7 +100,6 @@ app.post('/contest/:id/edit', async (req, res) => {
     if (!Array.isArray(req.body.problems)) req.body.problems = [req.body.problems];
     contest.problems = req.body.problems.join('|');
     if (!['noi', 'ioi', 'acm'].includes(req.body.type)) throw new ErrorMessage('无效的赛制。');
-    contest.type = req.body.type;
     contest.information = req.body.information;
     contest.start_time = syzoj.utils.parseDate(req.body.start_time);
     contest.end_time = syzoj.utils.parseDate(req.body.end_time);
diff --git a/views/contest_edit.ejs b/views/contest_edit.ejs
index b0118c4..e1cd562 100644
--- a/views/contest_edit.ejs
+++ b/views/contest_edit.ejs
@@ -22,19 +22,19 @@
               <label>赛制</label>
               <div class="field">
                 <div class="ui radio checkbox">
-                  <input type="radio" name="type" id="type-noi" value="noi"<% if (contest.type === 'noi') { %> checked="checked"<% } %>>
+                  <input <% if (contest.id) { %>disabled <% } %>type="radio" name="type" id="type-noi" value="noi"<% if (contest.type === 'noi') { %> checked="checked"<% } %>>
                   <label for="type-noi">NOI</label>
                 </div>
               </div>
               <div class="field">
                 <div class="ui radio checkbox">
-                  <input type="radio" name="type" id="type-ioi" value="ioi"<% if (contest.type === 'ioi') { %> checked="checked"<% } %>>
+                  <input <% if (contest.id) { %>disabled <% } %>type="radio" name="type" id="type-ioi" value="ioi"<% if (contest.type === 'ioi') { %> checked="checked"<% } %>>
                   <label for="type-ioi">IOI</label>
                 </div>
               </div>
               <div class="field">
                 <div class="ui radio checkbox">
-                  <input type="radio" name="type" id="type-acm" value="acm"<% if (contest.type === 'acm') { %> checked="checked"<% } %>>
+                  <input <% if (contest.id) { %>disabled <% } %>type="radio" name="type" id="type-acm" value="acm"<% if (contest.type === 'acm') { %> checked="checked"<% } %>>
                   <label for="type-acm">ACM</label>
                 </div>
               </div>