function chBgImg()
{
	img = new Array();

	img[0] = "/images/top/bg-01.jpg";
	img[1] = "/images/top/bg-02.jpg";
	img[2] = "/images/top/bg-03.jpg";
	img[3] = "/images/top/bg-04.jpg";
	img[4] = "/images/top/bg-05.jpg";

	n= Math.floor(Math.random()*img.length);
	document.body.style.backgroundImage = "url(" + img[n] + ")";
}