img = new Array();
img[0] = "j/images/topimage_00.jpg";
img[1] = "j/images/topimage_01.jpg";
img[2] = "j/images/topimage_02.jpg";
img[3] = "j/images/topimage_03.jpg";
img[4] = "j/images/topimage_04.jpg";

function setImage(){
	amount = img.length;
	No = Math.floor(Math.random()*amount);
	document.write("<a href='http://www.setsunan.ac.jp/nyushika/fitting/' target='_blank'><img src='" + img[No] + "' border='0'></a>");
}