diff --git a/app/controllers/memos_controller.rb b/app/controllers/memos_controller.rb
index e354a3293..9922aabbe 100644
--- a/app/controllers/memos_controller.rb
+++ b/app/controllers/memos_controller.rb
@@ -229,7 +229,7 @@ class MemosController < ApplicationController
   end
 
   def back_memo_url
-    forum_memo_path(@forum, (@memo.parent_id.nil? ? @memo : @memo.parent_id))
+    forum_memo_path(@forum, (@memo.root.nil? ? @memo : @memo.root))
   end
 
   def back_memo_or_forum_url
diff --git a/app/views/memos/show.html.erb b/app/views/memos/show.html.erb
index b03127247..a733da7c5 100644
--- a/app/views/memos/show.html.erb
+++ b/app/views/memos/show.html.erb
@@ -80,9 +80,9 @@
         <div nhname='div_form' class="mt10 ml80" style="display:none;">
         <%=  form_for(@memo_new, url: forum_memos_path, :method=>'post') do |f| %>
 
-              <%= f.hidden_field :subject, :required => true, value: @memo.subject %>
-              <%= f.hidden_field :forum_id, :required => true, value: @memo.forum_id %>
-              <%= f.hidden_field :parent_id, :required => true, value: @memo.id %>
+              <%= f.hidden_field :subject, :required => true, value: reply.subject %>
+              <%= f.hidden_field :forum_id, :required => true, value: reply.forum_id %>
+              <%= f.hidden_field :parent_id, :required => true, value: reply.id %>
               <%= hidden_field_tag :quote,"",:required => false,:style => 'display:none' %>
             <textarea name='memo[content]' style="display:none;"></textarea>
             <p nhname='contentmsg'></p>