The present invention provides a surface light source device capable of reducing luminance non-uniformity near point light sources and near between the point light sources adjacent to each other, and a display device of high display quality. The surface light source device includes: a plurality of LEDs arranged at a predetermined spacing; a light guide plate that emits, as a surface light, light emitted from the point light sources and entered into at least one side surface, through a light emission surface perpendicular to a light incident surface; reflecting sheets disposed respectively on a light anti-emission surface and near the LEDs in the light guide plate; and a casing having an opening part at a location corresponding to the light emission surface of the light guide plate, and holding the LEDs and the light guide plate and the reflecting sheets. The surface light source device further includes, near between the LEDs adjacent to each other, light introducing means for introducing the light emitted from the LEDs into the light emission surface or the light anti-emission surface.