A surface light source device includes a light source, a plurality of light guide rods that are disposed in parallel and allow light emitted from the light source to enter through an end surface and emits the incident light through an outer peripheral surface, and a diffusion plate that transmits light emitted from the light guide rod while diffusing the light. The light guide rod includes a light control part disposed on a surface along an axis of the light guide rod, and scattering, reflecting, or emitting light guided inside the light guide rod. Further, when an angle of a direction of a perpendicular relative to an extending direction of the diffusion plate from the center of the light guide rod is set as 0°, an angle of light having peak intensity to be emitted from the light guide rod is 30° to 90°.