<form name="form1">
<input type="button"name="disabled_button" value="ボタン"disabled>
<input type="text"name="count"size=5 readonly style="text-align:right">
</form>

<script language="JavaScript"><!--
set_time=5;     //ボタンの押せるまでの時間(秒)
//-------------------------
document.form1.count.value=set_time;
function disabled_time(){
set_time--;
document.form1.count.value=set_time;
if(set_time)
    setTimeout("disabled_time()", 1000);
else
    document.form1.disabled_button.disabled=false;
}
setTimeout("disabled_time()", 1000);
/*himajin.moo.jp*/
// --></script>