A semiconductor device includes a package and a cooler. The semiconductor package includes a semiconductor element, a metal member, and a molding member for encapsulating the semiconductor element and the metal member. The metal member has a metal portion thermally connected to the semiconductor element, an insulating layer on the metal portion, and a conducting layer on the insulating layer. The conducting layer is at least partially exposed outside the molding member and serves as a radiation surface for radiating heat of the semiconductor element. The cooler has a coolant passage through which a coolant circulates to cool the conducting layer. The conducting layer and the cooler are electrically connected together.