An illumination device for the rear license plate of a motor vehicle includes a carrier wall bearing the license plate, to which a wall area forming a projection is connected, which projects rearwards above the license plate with an approximately horizontal surface. An aperture is located on the projection side and a switchable light source is located thereabove. The aperture is covered by a transparent lens, with an overlapping edge of the lens fastened from below to a contact edge surrounding the aperture. Light radiated by the light source through the lens is radiated through the surface inside the overlapping edge to the license plate. The lens has a light-guiding and/or light-deflecting element which is arranged such that light is also passed to at least a partial area of the rear overlapping edge of the lens and radiated at a predetermined luminance, to the license plate.