A liquid crystal display device according to the present invention has a lighting unit (UT) comprising a light guiding plate (3), a light source (2), a reflector (4), a reflecting sheet (5) and a housing (10), and a liquid crystal display panel (1). In the liquid crystal display device, increase in temperature of the light source (2) is prevented by providing an opening portion (S1) on the housing (10) such that the opening portion (S1) reaches the reflector (4). In the liquid crystal display device, light emission intensity of the lighting unit (UT) is not lowered during operation of the device, and further, a lifetime of the light source (2) is not shortened.