A surface light source device, which may perform surface light emission using a plurality of light guide members while suppressing formation of emission lines, and a display device using the surface light source device is provided. The surface light source device includes light sources, and a plurality of light guide members, each light guide member having a light incidence surface for light entering from each of the light sources, and making surface light emission based on incident light from the light incidence surface. The plurality of light guide members are arranged on the same plane, and each light guide member has tapered or curved surfaces adjacent to the light incidence surface, each tapered or curved surface having a predetermined angle against the light incidence surface.