A semiconductor device according to the present invention includes: a semiconductor layer of a first conductivity type; a body region of a second conductivity type formed in a surface layer portion of the semiconductor layer; a trench dug from the surface of the semiconductor layer to penetrate the body region; a source region of a first conductivity type formed on a side portion of the trench in a surface layer portion of the body region; a gate insulating film formed on the bottom surface and the side surface of the trench; a gate electrode embedded in the trench through the gate insulating film and so formed that the surface thereof is lower by one stage than the surface of the source region; and a peripheral wall film formed on a peripheral edge portion of the surface of the gate electrode to be opposed to an upper end portion of the side surface of the trench.