A semiconductor device includes a semiconductor element and a lead part. The semiconductor element is mounted on a circuit pattern provided on an insulating substrate. The lead part has a plate shape and is bonded to the semiconductor element with a first bonding material interposed therebetween. The lead part includes a lead body and a bonding component. The lead body includes an opening part provided corresponding to a mounting position of the semiconductor element. The bonding component is provided in the opening part and on the semiconductor element. The bonding component is bonded at a lower surface thereof to the semiconductor element by the first bonding material and bonded at an outer peripheral part thereof to an inner periphery of the opening part by a second bonding material.