img = new Array();

img[0] = "http://www.roof-meister.com/image/cimage01.jpg";
img[1] = "http://www.roof-meister.com/image/cimage02.jpg";
img[2] = "http://www.roof-meister.com/image/cimage03.jpg";

n = Math.floor(Math.random()*img.length);

document.write("<img src='"+img[n]+"' border='0' alt='屋根リフォーム、雨漏り修理、屋根外装専門店' width='298' height='165'>");