A space having a certain thickness is provided between a metal base and a heat-dissipation fin set or the like. A semiconductor device is provided, including: a package portion; a metal base which is housed in the package portion and is exposed at a lower surface of the package portion; a semiconductor chip which is housed in the package portion and is placed above the metal base; and a frame portion provided to surround a penetration space penetrating the package portion, wherein a lower end of the frame portion protrudes below the lower surface of the package portion and a lower surface of the metal base. It is preferable that the frame portion is inserted in the penetration space after the penetration space is formed in the package portion.