A semiconductor device has a drift region (20) (third semiconductor region) of an n-type (first conductivity type); a body region (50) (second semiconductor region) of a p-type (second conductivity type) provided on the drift region (20); an emitter region (60) (first semiconductor region) of the n-type formed in the top surface of the body region (50) and separated from the drift region (20) by the body region (50); a trench (14) extending from the top surface of the emitter region (60) through the body region (50) into the drift region (20); a trench gate electrode (13) filled in the trench (14); and a semiconductor region (70) (fourth semiconductor region) of the p-type formed in contact with side faces of the trench protruding into the drift region (20). Therefore, the semiconductor device can suppress a surge voltage at turn-off, and can be produced easily.