A backlight of a liquid crystal display device includes lamps and a conductive board. Each lamp has electrodes, one of which is contacted and retained by a contact terminal on the conductive board. The contact terminals are electrically connected by the conductive board. A bent part located in the conductive board is disposed between adjacent contact terminals such that when heat from the lamps absorbed by the conductive board expands the conductive board, the bent part is resiliently deformed to maintain the distance between the lamps.