//減らしたい、増やしたい日数を引数に

function showDate(num,text){

	today = new Date();
	myDate = today.getDate();
	myDate += num;
	today.setDate(myDate);

	myYear  = today.getFullYear();
	myMonth = today.getMonth() + 1;
	myDate = today.getDate();

	myMessage   = text + myYear + "年" + myMonth + "月" + myDate + "日";

	document.write(myMessage);

}