A semiconductor device including an active cell region formed over the surface of a silicon substrate and including a vertical MOSFET, a drain electrode formed over the surface of the silicon substrate and leading out the drain of the vertical MOSFET from the back surface of the silicon substrate, an external drain terminal formed over the drain electrode, and a source electrode formed over the active cell region so as to be opposed to the drain electrode at least along three sides at the periphery of the external drain terminal over the active cell region and connected to the source of the vertical MOSFET.