A light guide plate display device includes a light guide plate, a plurality of light source devices, and a plurality of prisms. The light guide plate includes a display face and a plurality of end faces, and is formed of a light transmitting material. The light source devices are provided along respective end faces of the light guide plate, and radiate light from the end face toward an inside of the light guide plate. The prisms are formed inside the light guide plate. The prisms respectively have a plurality of side faces which face the respective light source devices. The respective side faces are inclined at least in two stages of a transmitting inclined face which transmits light radiated from the light source device, and a reflecting inclined face which reflects the light radiated from the light source device, and outputs the light to the display face, in a thickness direction of the light guide plate.