A display device includes a transmissive liquid crystal display panel that is disposed on a front side of a display medium that effects variable display, and an area light source device that is disposed between the liquid crystal display panel and the display medium and illuminates a back surface of the liquid crystal display panel. The area light source device includes a light source, and a light guide that includes a transmissive display part, which is opposed to the display medium, and emits light, which is radiated from the light source, toward the liquid crystal display panel. The light guide is configured such that a thickness at an end face along an edge that defines the transmissive display part is less than a thickness at a surface of the light guide, which is opposed to the light source.