function smartRollover() {
	if(document.getElementsByTagName) {
		var images = document.getElementsByTagName("img");

		for(var i=0; i < images.length; i++) {
			if(images[i].getAttribute("src").match("_off."))
			{
				images[i].onmouseover = function() {
					this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));
				}
				images[i].onmouseout = function() {
					this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));
				}
			}
		}
	}
}

if(window.addEventListener) {
	window.addEventListener("load", smartRollover, false);
}
else if(window.attachEvent) {
	window.attachEvent("onload", smartRollover);
}

MM_preloadImages(
'http://www.mta-office.com/images/common/bt1_on.jpg',
'http://www.mta-office.com/images/common/bt2_on.jpg',
'http://www.mta-office.com/images/common/bt3_on.jpg',
'http://www.mta-office.com/images/common/bt4_on.jpg',
'http://www.mta-office.com/images/common/bt5_on.jpg',
'http://www.mta-office.com/images/common/bt6_on.jpg',
'http://www.mta-office.com/images/common/bt_pagetop_on.jpg',
'http://www.mta-office.com/images/common/logo_on.jpg',
'http://www.mta-office.com/images/common/side_access_bt_on.jpg',
'http://www.mta-office.com/images/common/side_consul_bt_on.jpg',
'http://www.mta-office.com/images/common/side_service1_on.jpg',
'http://www.mta-office.com/images/common/side_service2_on.jpg',
'http://www.mta-office.com/images/common/side_service3_on.jpg',
'http://www.mta-office.com/images/common/side_tel_bt_on.jpg',
'http://www.mta-office.com/images/common/tel_bt_on.jpg',
'http://www.mta-office.com/images/top/info_list_bt_on.jpg',
'http://www.mta-office.com/images/top/detail_on.jpg',
'http://www.mta-office.com/images/top/voice_detail_on.jpg',
'http://www.mta-office.com/images/voice/voice_img_bt_on.jpg',
'http://www.mta-office.com/images/voice/bt_detail_on.jpg',
'http://www.mta-office.com/images/service/iin/bt_igyou_on.jpg',
'http://www.mta-office.com/images/service/so/bt_igyou_on.jpg',
'http://www.mta-office.com/images/service/so/bt_ippan_on.jpg',
'http://www.mta-office.com/images/service/kigyou/bt_kigyou_on.jpg'
);

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}