NITRIDE SEMICONDUCTOR DEVICE

A nitride semiconductor device includes a substrate, a first nitride semiconductor layer, a first high-resistance semiconductor layer, a first p-type nitride semiconductor layer, and a second high-resistance semiconductor layer that are arranged sequentially from a lower side; an electron mobility layer and an electron supply layer covering a first opening that penetrates through the second high-resistance semiconductor layer, the first p-type nitride semiconductor layer, and the first high-resistance semiconductor layer; a potential-fixing electrode that is disposed in contact with the first p-type nitride semiconductor layer; and an insulating film that covers a gate electrode and a source electrode. The insulating film is disposed along an inner surface of a groove portion that is disposed in an end portion of the nitride semiconductor device, and penetrates through the first p-type nitride semiconductor layer. The first high-resistance semiconductor layer is a high-resistance AlGaN layer.