A semiconductor device according to an embodiment including: a semiconductor layer having a first plane and a second plane, the semiconductor layer including: a first trench on the first plane; a second trench on the second plane; a first conductivity first semiconductor region; a second conductivity type second semiconductor region between the first semiconductor region and the first plane; a first conductivity type third semiconductor region between the second semiconductor region and the first plane; a second conductivity type fourth semiconductor region between the third semiconductor region and the first plane; and a first conductivity type fifth semiconductor region provided between the second trench and the third semiconductor region in contact with the second trench; a first gate electrode in the first trench; a second gate electrode in the second trench; a first electrode on the first plane; and a second electrode on the second plane.