An area light source device includes an L-shaped cold-cathode fluorescent lamp, a wedge-shaped light guide having an incidence surface, on which emission light from the cold-cathode fluorescent lamp is incident, and a reflector that surrounds the cold-cathode fluorescent lamp, has an opening facing the incidence surface, and reflects the emission light from the cold-cathode fluorescent lamp toward the light guide, wherein the opening of the reflector has a shape corresponding to shapes of two mutually neighboring incidence surfaces of the light guide.