The present invention provides a liquid crystal display device which can largely enhance a property of focusing light from a backlight. The backlight arranged on a back surface of a liquid crystal panel includes a light guide plate, a light source, a first asymmetrical prism sheet, and a second asymmetrical prism sheet. A reflection surface having an inclination of 2.degree. or less for guiding light from the light source toward the liquid crystal display panel is formed on a back surface of the light guide plate. The first asymmetrical prism sheet and the second asymmetrical prism sheet respectively include projecting portions which extend in the arrangement direction of the light source and are arranged in parallel to each other in the direction which intersects the arrangement direction of the light source.