Okay, first give one attribute to your div first, i.e
runat="server"
.
Like this :
<div ID="div1" runat="server">
<%#Eval("YourColumName")%>
</div>
So finally, your code would be :
<asp:imagebutton id="Img_Up_vote" runat="server" onclientclick="upvote(this);return false;" xmlns:asp="#unknown">
ImageUrl="~/images/up.png" data-JobID='<%#Eval("OrgJob_id")%>' />
<br />
<div id="vote_score" runat="server">
<%#Eval("VoteCount")%></div>
<br /></asp:imagebutton>
-KR