<!DOCTYPE html> <html lang="ja-JP"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width,user-scalable=yes,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.5"> <title></title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script> $(function(){ $(":text").focus(function(){ $(this).after("<strong>必須項目です</strong>"); }).blur(function(){ $("strong").remove(); }); }); </script> <body> お名前:<input type="text" name="name"> </body> </html>