According to one embodiment, a semiconductor device includes a first electrode, a second electrode, and a semiconductor layer between the first electrode and the second electrode. A third electrode is in the semiconductor layer. The third electrode extends in a second direction orthogonal to the first direction. A plurality of fourth electrodes are connected to the second electrode and extend in the first direction into the semiconductor layer. The fourth electrodes are spaced from one another along the second direction. A fifth electrode that is electrically isolated from the first electrode and between the first electrode and the plurality of fourth electrodes. The fifth electrode extends in the second direction and contacts the lower ends of the plurality of fourth electrodes in the trench.