A surface light source apparatus includes: a fluorescent discharge tube having a bent portion; a light guide plate which has a corner portion facing the bent portion; a rear frame which receives the light guide plate and is formed of a resin material; and a middle frame which is provided parallel with the rear frame and is formed of a resin material. The rear frame or the middle frame has a protrusion which is in contact with the corner portion. The bent portion of the fluorescent discharge tube is disposed in a gap between the protrusion and the side surface of the rear frame.