diff --git a/lib/t2hs.rb b/lib/t2hs.rb
index f532c01..d8eb0be 100755
--- a/lib/t2hs.rb
+++ b/lib/t2hs.rb
@@ -981,6 +981,9 @@ def exec_inline_start_command(command)
           @style_stack.push([command,"</#{found[1]}>"])
           push_chars("<#{found[1]} class=\"#{filter.call(found[0])}\">")
         else
+          if $DEBUG
+            puts "警告(#{line_number}行目):「#{key}」は未対応のコマンドのため無視します"
+          end
           nil
         end
       end