A liquid crystal display device which can make the surface brightness of an edge-light-type backlight uniform is provided. The liquid crystal display device includes a liquid crystal display panel and a backlight which radiates light to the liquid crystal display panel. The backlight includes a light guide plate which is arranged on a back side of the liquid crystal display panel, a light source arranged on an outer peripheral portion of a first main surface of the light guide plate which faces the liquid crystal display panel in an opposed manner, and a reflection sheet which is arranged on a back side of the light guide plate as viewed from the liquid crystal display panel. The light guide plate is made of a transparent resin having a refractive index of 1.53 or less. On a surface of the light guide plate opposite to the first main surface, a second main surface which is substantially parallel to the first main surface and a plurality of inclined surfaces which are inclined at a preset angle with respect to the second main surface are formed. An angle of the inclined surface positioned near a position at which light from the light source is incident and an angle of the inclined surface positioned remote from the position at which the light from the light source from the light source is incident differ from each other.