According to one embodiment, a second nitride semiconductor layer is provided on a first nitride semiconductor layer and has a band gap wider than that of the first nitride semiconductor layer. A third nitride semiconductor layer is provided above the second nitride semiconductor layer. A fourth nitride semiconductor layer is provided on the third nitride semiconductor layer and has a band gap wider than that of the third nitride semiconductor layer. A fifth nitride semiconductor layer is provided between the second and the third nitride semiconductor layers. A first electrode contacts the second, the third and the fourth nitride semiconductor layers. A second electrode is provided on the fourth nitride semiconductor layer. A gate electrode is provided on a gate insulating layer between the first and the second electrodes. A third electrode is in contact with the second nitride semiconductor layer.