function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		kaisya_over = newImage("images/kaisya-over.gif");
		keiei_over = newImage("images/keiei-over.gif");
		saiyo_over = newImage("images/saiyo-over.gif");
		map_over = newImage("images/map-over.gif");
		contact_over = newImage("images/contact-over.gif");
		menu1_0_shiroyama_over = newImage("images/menu1-0_shiroyama-over.gif");
		menu1_1_gijyutsu_over = newImage("images/menu1-1_gijyutsu-over.gif");
		menu1_2_soshiki_over = newImage("images/menu1-2_soshiki-over.gif");
		menu1_3_new_over = newImage("images/menu1-3_new-over.gif");
		menu2_1_setsubi_over = newImage("images/menu2-1_setsubi-over.gif");
		menu3_1_car_over = newImage("images/menu3-1_car-over.gif");
		menu3_2_oa_over = newImage("images/menu3-2_oa-over.gif");
		menu4_1_epo_over = newImage("images/menu4-1_epo-over.gif");
		preloadFlag = true;
	}
}