A semiconductor device which combines reliability and the guarantee of electrical characteristics is provided. A power MOSFET and a protection circuit formed over the same semiconductor substrate are provided. The power MOSFET is a trench gate vertical type P-channel MOSFET and the conduction type of the gate electrode is assumed to be P-type. The protection circuit includes a planar gate horizontal type offset P-channel MOSFET and the conduction type of the gate electrode is assumed to be N-type. These gate electrode and gate electrode are formed in separate steps.