A planar illumination device includes a light source unit, including a substantially planar emitting surface, configured to emit light to illuminate a substantially planar object, and a frame, formed in a frame shape enclosing the light source unit, disposed on an outer circumferential side of the light source unit, configured to hold the light source unit. The frame includes a reflecting part configured to reflect the light, and an absorbing part, formed integral with at least a part of an outer circumferential surface of the reflecting part, configured to absorb the light. The reflecting part and the absorbing part include joint interface therebetween that is inclined to a direction vertical to the emitting surface.