A semiconductor light-emitting device including a favorable radiating structure can include a semiconductor light source sealed between a metallic cap having a light-emitting window and a metallic base attached on a heat sink plate. The semiconductor light-emitting device can also include a holder attaching the metallic base along the metallic cap between the holder and the heat sink plate to efficiently radiate heat generated from the light source, and a thermal interface material layer disposed between at least a top surface of the heat sink plate and an outer bottom surface of the holder so as to be able to enlarge each tolerance of parts composing the light-emitting device. Thus, the disclosed subject matter can provide semiconductor light-emitting devices including the favorable radiating structure, which can be employed for various lighting apparatuses including a headlight in a relatively small size by selecting the semiconductor light source incorporated in the devices.