A liquid crystal display device is provided to display a good image in which luminance non-uniformity is suppressed even though an illumination device is slimmed. A white beam of a fluorescent tube(2) is incident on a liquid crystal panel as a backlight after the white beam of the fluorescent tube is diffused and reflected several times between a reflective sheet(5) and a diffusive plate(11). At least one pin mold hole(10a) is arranged in the reflective sheet to support central surroundings of the diffusive plate. Luminance non-uniformity is prevented due to a shorter distance from the reflective sheet to the diffusive plate by preventing deformation of the diffusive plate due to heat expansion of the diffusive plate caused by heat of the fluorescent tube.
