var randObjects=[
	'<img src="img/top/img_main1.jpg" alt="馬業界求人・就職ナビ">',
	'<img src="img/top/img_main2.jpg" alt="馬業界求人・就職ナビ">',
	'<img src="img/top/img_main3.jpg" alt="馬業界求人・就職ナビ">'
];
function randWrite() {
	var rr = parseInt(Math.random() * randObjects.length);
	document.write(randObjects.slice(rr,rr+1)[0]);
	randObjects.splice(rr,1);
}