//ヘッダーのランダム画像

var iValue, rNumber;

var img1 = new Image();
var img2 = new Image();
var img3 = new Image();
var img4 = new Image();
var img5 = new Image();
img1.src = "images/header_img1.jpg";
img2.src = "images/header_img2.jpg";
img3.src = "images/header_img3.jpg";
img4.src = "images/header_img4.jpg";
img5.src = "images/header_img5.jpg";

function DisplayImage() {
	iValue = Math.random() * 5;
	rNumber= Math.ceil(iValue);
	if(rNumber==0) rNumber++;
	document.headerimg.src = eval("img" + rNumber + ".src");
}