According to one embodiment, a method for manufacturing a semiconductor device includes: forming a plurality of trenches; forming a gate insulating film; burying a gate electrode; burying an insulating member; projecting the insulating member; forming a base layer; forming a mask film; forming a first semiconductor layer; forming a carrier ejection layer; forming a first electrode; and forming a second electrode. The projecting includes projecting the insulating member from the upper surface of the semiconductor substrate by removing an upper layer portion of the semiconductor substrate. The mask film is formed so as to cover the projected insulating member. The forming the first semiconductor layer includes forming a first semiconductor layer of the first conductivity type in an upper layer portion of the base layer by doping the base layer with impurity, the upper layer portion having a lower surface below an upper end of the gate electrode.