<p class="goTop"><a href="#">맨위로</a></p> 

.goTop {
  width: 42px;
  height: 42px;
  background: #5acbd7;
  border-radius: 50%;
  opacity: 0.7;
  z-index: 100;
  a {
    display: block;
    padding-top: 22px;
    padding-top: 2.2rem;
    color: #fff;
    text-align: center;
    font-size: 11px;
    background: url("../../images/mo/ico_gnb.png") no-repeat 0 0;
    background-size: 320px 400px;
    background-position: -32px -137px;
  }
}
 

<script>
$(".goTop").hide();
$('.goTop').click(function(){
$('html, body').animate({scrollTop:0}, 300);
});
$(window).scroll(function(){
var conH = $("footer").height() + 90;
temp = $(window).scrollTop();
if( temp = $(window).scrollTop() ) {
$(".goTop").fadeIn();
} else {
$(".goTop").fadeOut();
}
$(".goTop").css({"position" : "fixed" , "bottom" : conH + "px" , "right" : "5px"});
});
</script>

<div id="wrapper"></div>

#toTop {
display:none;
text-decoration:none;
position:fixed;
bottom:10px;
right:10px;
overflow:hidden;
width:51px;
height:51px;
border:none;
text-indent:100%;
background:url(../img/ui.totop.png) no-repeat left top;
}


#toTopHover {
background:url(../img/ui.totop.png) no-repeat left -51px;
width:51px;
height:51px;
display:block;
overflow:hidden;
float:left;
opacity: 0;
-moz-opacity: 0;
filter:alpha(opacity=0);
}


#toTop:active, #toTop:focus {
outline:none;
}

<script src="js/jquery-1.7.2.min.js" type="text/javascript"></script>
<script src="js/easing.js" type="text/javascript"></script>
<script src="js/jquery.ui.totop.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function() {
/*
var defaults = {
  containerID: 'toTop', // fading element id
containerHoverID: 'toTopHover', // fading element hover id
scrollSpeed: 1200,
easingType: 'linear' 
  };
*/

$().UItoTop({ easingType: 'easeOutQuart' }); 
});
</script>

Download: http://mattvarone.com/web-design/uitotop-jquery-plugin/