A light-emitting device according to the present invention includes a first electrode unit for injecting an electron, a second electrode unit for injecting a hole, and light-emitting units and electrically connected to the first electrode unit and the second electrode unit respectively, wherein the light-emitting units and are formed of single-crystal silicon, the light-emitting units and having a first surface (topside surface) and a second surface (underside surface) opposed to the first surface, plane orientation of the first and second surfaces being set to a (100) plane, thicknesses of the light-emitting units and in a direction orthogonal to the first and second surfaces being made extremely thin.