According to one embodiment, a semiconductor device includes: a first region including: a first semiconductor layer; a first semiconductor region; a second semiconductor region; a third semiconductor region having higher impurity concentration than the first semiconductor region; a first electrode; a second electrode; an insulating film; a third electrode; a fourth electrode, a second region including a pad electrode, and the third region including: the first semiconductor layer; the first semiconductor region; a third semiconductor region; the first electrode; the second electrode; and a first insulating layer.