Edit in JSFiddle

$(document).ready(function(){
    $('.up').click(function(){
         move_up();
    });
    $('.down').click(function(){
         move_down();
    });
});
function move_up(e){                   
        var pos=document.getElementById("item_image").scrollTop;
        document.getElementById('item_image').scrollTop=pos+10;
}
function move_down(e){
        var pos=document.getElementById("item_image").scrollTop;
        document.getElementById('item_image').scrollTop=pos-10;            
}

<div class="item_image" id="item_image">
        <table width="50%" align=center >
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
            <tr><td>code srilanka</td></tr>
    </table>
</div>   
<input type="button"  class="up" value="UP">
<input type="button" class="down" value="DOWN">
 

div{
    text-align:center; 
    height:100px; 
    overflow:scroll;
    width:50%;
    margin-left:20%;
    margin-right:20%;
}