A liquid crystal display device includes a liquid crystal display panel and a backlight disposed at a rear surface of the liquid crystal display panel. The backlight includes a light source, a frame housing the light source, a heat dissipating plate disposed inside the frame, and a reflective sheet disposed at a surface of the heat dissipating plate on the liquid crystal display panel side. The heat dissipating plate is formed with a heat dissipating fin protruding to a surface of the frame on the side opposite to the liquid crystal display panel through an opening formed through the frame in a portion corresponding to the upper portion thereof and formed with an opening which is closed with the frame and the reflective sheet in a portion corresponding to the lower portion thereof.