A first heat sink has a first inner surface and a first outer surface, and has a first through hole. A second heat sink has a second inner surface disposed with a clearance left from the first inner surface of the first heat sink, and a second outer surface opposite to the second inner surface, and has a second through hole. A semiconductor element is disposed within a clearance between the first inner surface of the first heat sink and the second inner surface of the second heat sink. A sealing member seals the semiconductor element within the clearance between the first inner surface and the second inner surface. A first hollow tube is made of metal, and connects the first through hole and the second through hole.