In an illumination device for license plate which illuminates the license plate from the front side thereof, at least one light source consist of a white LED is arranged at a position upward or obliquely upward of the license plate in such a manner that optical axes thereof traverse with a lower range than the center of the license plate, and a reflector is arranged at a position obliquely downward seen from an observer's side of the light source, receiving a light directing to the observer's side from a portion of a light emitted from the light source, and converting the light into a light irradiating the center or the lower part of the license plate. Further, a garnish for accommodating the light source and having a light transmitting part can be provided to the illumination device.