function smartOver() {
	smartRollover('all');	//ロールオーバーを適用させたい箇所のIDを指定
}
function smartRollover(idName) {
	if(document.getElementsByTagName) {
		var images = document.getElementById(idName).getElementsByTagName("img");
		for(var i=0; i < images.length; i++) {
			if(images[i].getAttribute("src").match(/_off\./))
			{
			fileName = new Array(images[i].getAttribute("src").replace("_off.", "_on."));
			preImages = new Array();
			for (j=0; j<fileName.length; j++)
			{
				preImages[j] = new Image();
				preImages[j].src = fileName[j];		//「_on」の画像をプリロード
			}
				images[i].onmouseover = function() {
					this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));	//マウスオーバーで_off→_on
				}
				images[i].onmouseout = function() {
					this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));	//マウスが離れたら_on→_off
				}
			}
		}
	}
}
if(window.addEventListener) {
	window.addEventListener("load", smartOver, false);	//実行
}
else if(window.attachEvent) {
	window.attachEvent("onload", smartOver);
}
else{
	window.onload = smartOver;
}