var imageDir = _dir + "common/images/";
	var preLoadList;
	var action = "false";

	function preLoad(){
		preLoadList = new Array(
	// left navigation
			"bnavi_pic_0100d.gif","bnavi_pic_0100e.gif",
			"bnavi_pic_0101d.gif","bnavi_pic_0101e.gif",
			"bnavi_pic_0102d.gif","bnavi_pic_0102e.gif",
			"bnavi_pic_0103d.gif","bnavi_pic_0103e.gif",
			"bnavi_pic_0104d.gif","bnavi_pic_0104e.gif",
			"bnavi_pic_0200d.gif","bnavi_pic_0200e.gif",
			"bnavi_pic_0201d.gif","bnavi_pic_0201e.gif",
			"bnavi_pic_0202d.gif","bnavi_pic_0202e.gif",
			"bnavi_pic_0203d.gif","bnavi_pic_0203e.gif",
			"bnavi_pic_0204d.gif","bnavi_pic_0204e.gif",
			"bnavi_pic_0300d.gif","bnavi_pic_0300e.gif",
			"bnavi_pic_0301d.gif","bnavi_pic_0301e.gif",
			"bnavi_pic_0302d.gif","bnavi_pic_0302e.gif"
		);
		onImages = new Array();
		for(field in preLoadList){
			onImages[field] = new Image();
			onImages[field].src = imageDir + preLoadList[field];
		}
		action = "true";
	}

	function preLoadService(){}

	function preLoadRecruit(){
		preLoadList = new Array(
			"submit_r000d.gif","submit_r000e.gif",
			"submit_r100d.gif","submit_r100e.gif"
		);
		onImages = new Array();
		for(field in preLoadList){
			onImages[field] = new Image();
			onImages[field].src = imageDir + preLoadList[field];
		}
	}

	function preLoadContact(){
		preLoadList = new Array(
			"submit_c000d.gif","submit_c000e.gif",
			"submit_c001d.gif","submit_c001e.gif"
		);
		onImages = new Array();
		for(field in preLoadList){
			onImages[field] = new Image();
			onImages[field].src = imageDir + preLoadList[field];
		}
	}

	function changeImage(fileName, imageName){
		if (action == "true"){
			document.images[imageName].src = imageDir + fileName;
		}
	}

	function changeImageAllOff(){
		changeImage('header_navi_0000d.gif', 'home');
		changeImage('header_navi_0001d.gif', 'service');
		changeImage('header_navi_0002d.gif', 'company');
		changeImage('header_navi_0003d.gif', 'recruit');
		changeImage('header_navi_0004d.gif', 'contuct');
	}