A semiconductor device of an embodiment includes a silicon carbide layer having a first plane and a second plane; a trench having a first side face, a second side face, and a bottom face; a first silicon carbide region of a first conductivity type; a second silicon carbide region and a third silicon carbide region of a second conductivity type, the third silicon carbide region and the second silicon carbide region sandwiching the trench; a sixth silicon carbide region of a second conductivity type in contact with the second side face and the bottom face; and a gate electrode in the trench. The first side face has a first region having a first inclination angle. The off angle of the first region with respect to a {0-33-8} face is no more than 2 degrees. A second inclination angle of the second side face is larger the first inclination angle.