A semiconductor device, including: an intermediate plate; a semiconductor element connected to one of surfaces of the intermediate plate by a brazing filler metal; a main plate connected to the other one of the surfaces of the intermediate plate by a brazing filler metal; and a resin layer, the intermediate plate having an external region extending to an outer side with respect to a region in which the intermediate plate is connected to the brazing filler metal, a first through-hole extending through the intermediate plate in the external region, the resin layer covering at least the brazing filler metal, the intermediate plate and a surface of the main plate in which the main plate faces the intermediate plate, the resin layer being also arranged inside the first through-hole.