diff --git a/app/controllers/announcements_controller.rb b/app/controllers/announcements_controller.rb
index df75c45..5f7f556 100644
--- a/app/controllers/announcements_controller.rb
+++ b/app/controllers/announcements_controller.rb
@@ -89,7 +89,7 @@ class AnnouncementsController < ApplicationController
         }
       end
     {
-      "title" => a.title,
+      "title" => HTMLEntities.new.encode(a.title),
       "subtitle" => a.subtitle,
       "statuses" => statuses,
       "category" => a.category.title,
@@ -135,7 +135,7 @@ class AnnouncementsController < ApplicationController
         }
       end
       {
-        "title" => a.title,
+        "title" => HTMLEntities.new.encode(a.title),
         "subtitle" => a.subtitle,
         "statuses" => statuses,
         "category" => a.category.title,
@@ -218,7 +218,7 @@ class AnnouncementsController < ApplicationController
         "tag-cloud" => tags,
         "data" => {
           "tag-cloud-title" => t("announcement.tag_cloud"),
-          "title" => announcement.title,
+          "title" => HTMLEntities.new.encode(announcement.title),
           "categories-title" => t("announcement.categories"),
           "update_user" => update_user,
           "updated_at" => announcement.postdate.strftime('%Y-%m-%d %H:%M'),