A surface light source device 1 includes a base member 3 provided with a plurality of point-source lines, each of which has a plurality of point sources 11 arranged in a line, and a plurality of diffuse transmission members 14 for covering the point-source lines. Each of the diffuse transmission members 14 is located while keeping substantially equal distances from the respective point sources 11 at least in a direction perpendicular to each of the point-source lines. Consequently, it is possible to allow light fluxes emitted from the point sources 11 to be transmitted in diffusion through the diffusion transmission members 14.