A light emitting device comprises: a surface light source for a surface-emission; a CPC lens having a light receiving surface, a side reflective surface, and a light emitting surface, the light receiving surface receiving a part of light from the surface light source, the side reflective surface reflecting the light from the light receiving surface, and the light emitting surface facing the light receiving surface and emitting the light; and a reflector containing the surface light source and the CPC lens, and having a concaved reflective surface for reflecting forward the light deviating the light receiving surface from the surface light source, wherein a ratio of a illumination area of the surface light source to an area of the light receiving surface of the CPC lens is not less than 0.63 and not more than 2.93.