The nitride semiconductor device and manufacturing method thereof

It includes a substrate, a first nitride semiconductor layer (1) on a substrate, are stacked on the first nitride semiconductor layer (1), a large gap than that of the first nitride semiconductor layer (1) with, defines reaches the bottom of the first nitride semiconductor layer (1) through the second nitride semiconductor layer (2) of the groove portion, the groove inner wall portion (11) and the second nitride semiconductor layer (2) covered and stacked a gate electrode, than in the first nitride semiconductor layer (1) a large band gap of the third nitride semiconductor layer (12), the groove in the upper portion (11) formed on the third nitride semiconductor layer (12) (5), respectively formed on the gate electrode (5) and a second ohmic electrode on both lateral sides (4a) and a second ohmic electrode (4b).