PURPOSE: A backlight assembly and a liquid crystal display device having the same are provided to prevent the center part of a diffusion plate from convexly swelling in spite of the expansion of the diffusion plate by the moisture or heat. CONSTITUTION: A backlight assembly includes a receiving container(480) formed with a shoulder part(485) on an inner wall to receive a diffusion plate(460). The shoulder part is apart from a side surface of the diffusion plate by a predetermined distance to prevent the center part of the diffusion plate from swelling by allowing the expansion of the diffusion plate when the diffusion plate absorbs moisture or heat. The receiving container further has first to fourth fixing protrusions(481-484) on first to fourth side walls(480a-480d) to fix the diffusion plate and prevent the movement of the diffusion plate by any impact.
