A semiconductor device of embodiments includes: a first electrode; a second electrode; a semiconductor layer provided between the first electrode and the second electrode, having a first face and a second face, and containing silicon; a first semiconductor region of n-type; a second semiconductor region of p-type disposed the first semiconductor region and the first face; a third semiconductor region of n-type between the second semiconductor region and the first face; a gate electrode facing the second semiconductor region; and a metal silicide layer between the first electrode and the second semiconductor region and between the first electrode and the third semiconductor region, including a top surface, a first bottom surface in contact with the third semiconductor region, and containing gold or a platinum group element. The n-type impurity concentration in the third semiconductor region monotonically decreases from the first bottom surface toward the second electrode.