According to an embodiment, a semiconductor device 1 includes a semiconductor substrate 50 including an upper surface, a trench electrode 22 provided inside a trench 20 formed on the upper surface, and a trench insulating film 21 provided between the trench electrode 22 and the semiconductor substrate 50. The semiconductor substrate 50 includes a first semiconductor layer of a first conductivity type, a lower end of the trench electrode 22 reaching the first semiconductor layer, a deep layer 19 of a second conductivity type partially provided on the first semiconductor layer in contact with the trench insulating film 21, a second semiconductor layer of the second conductivity type provided on the first semiconductor layer and on the deep layer 19 in contact with the trench insulating film 21, and a third semiconductor layer of the first conductivity type provided on the second semiconductor layer above the deep layer 19.