A planar light source device is provided which has high light extraction efficiency and in which a change in color tone at different viewing angles is small. The planar light source device includes, on a light emitting surface, a concavo-convex structure layer made of a resin composition. In this planar light source device, the concavo-convex structure layer has a cone, pyramid, or prism shape, and the resin composition contains a transparent resin and particles. In particular, in the planar light source device, variations in any of x- and y-chromaticity coordinates in any directions in a hemisphere on the light emitting surface are within ±0.1, the diameter of the particle is 10 μm or less, and the amount of the particles is 1 to 40 wt % based on the total amount of the resin composition. In addition, the difference in refractive index between the particles and the transparent resin is 0.05 to 0.5.