if (document.images) {

	// 画像1
	var img1on = new Image();
	img1on.src = "images/A_on.gif";
	var img1off = new Image();
	img1off.src = "images/A_off.gif";

	// 画像2
	var img2on = new Image();
	img2on.src = "images/B_on.gif";
	var img2off = new Image();
	img2off.src = "images/B_off.gif";

	// 画像3
	var img3on = new Image();
	img3on.src = "images/C_on.gif";
	var img3off = new Image();
	img3off.src = "images/C_off.gif";

	// 画像4
	var img4on = new Image();
	img4on.src = "images/D_on.gif";
	var img4off = new Image();
	img4off.src = "images/D_off.gif";

}

//マウスオーバー処理
function On(name) {

	if (document.images) {

		document.images[name].src = eval(name + 'on.src');

	}

}

//マウスアウト処理
function Off(name) {

	if (document.images) {

		document.images[name].src = eval(name + 'off.src');

	}

}