diff --git a/app/views/student_work/_evaluation_un_group_title.html.erb b/app/views/student_work/_evaluation_un_group_title.html.erb
index d782fe7f..45756245 100644
--- a/app/views/student_work/_evaluation_un_group_title.html.erb
+++ b/app/views/student_work/_evaluation_un_group_title.html.erb
@@ -36,7 +36,7 @@
       <a href="/users/<%= (student_work.user.try(:login)) %>" class="color-grey3"><%= student_work.user.show_real_name %></a>
     </td>
     <% group_id = @members.select{|m|m.user_id==student_work.user_id}.first.try(:course_group_id) %>
-    <% group_name = group_id.to_i == 0 ? '未分班' : @course.course_groups.find_by_id(group_id).name %>
+    <% group_name = group_id.to_i == 0 ? '未分班' : @course.course_groups.find_by_id(group_id).try(:name) %>
     <td title="<%= group_name %>">
       <span class="task-hide" style="display: block;max-width: 120px;"><%= group_name %></span>
     </td>