var delay = 16;
var divide = 8;

var timer;

// ページ先頭にスクロール
function scrollToTop(){
	var move;
	var nowY = 0;
	var targetY = 0;
	
	if(timer){ clearTimeout(timer); }
	
	if (document.all) {
		//move = nowY = document.body.scrollTop;
		move = nowY = document.documentElement.scrollTop;
	} else if (window.pageYOffset) {
		move = nowY = window.pageYOffset;
	} else {
		move = nowY = 0;
	}
	
	move += (targetY - nowY) / divide;
	if(move < 0){
		move = 0;
	}
	
	window.scrollTo(0,Math.floor(move));
	
	if(nowY != targetY){
		timer = setTimeout('scrollToTop()',delay);
	}
}