A motorcycle taillight includes a base, a light source unit, and a hood. The base includes a first bulb seat, which receives a primary light source of a light source unit mounted therein. An extension section extends from an underside of the first bulb seat in a direction toward the rear side of the motorcycle. The extension section has an underside to which a second bulb seat is mounted. The second bulb seat is located at a free end of the extension section to receive a license plate light of the light source unit mounted therein. The hood has a shielding section corresponding in position to the second bulb seat of the base. A cover is arranged under the shielding section. As such, the white light that is used to illuminate a license plate cannot be seen from the rear side of the motorcycle.