In an n-channel type power MISFET, a source electrode in contact with an n⁺-semiconductor region (source region) and a p⁺-semiconductor region (back gate contact region) is constituted with an Al film and an underlying barrier film comprised of MoSi₂, use of the material having higher barrier height relation to n-Si for the barrier film increasing the contact resistance to n-Si and backwardly biasing the emitter and base of a parasitic bipolar transistor making it less tending to turn-on, thereby decreasing the leak current of power MISFET.