A nitride semiconductor device enabiling to supress current collapse and manufacturing method thereof including a III-V group nitride semiconductor layer formed of III group elements includes at least one element from the group consisting of gallium, aluminum, boron and indium, and V group elements including at least nitrogen from the group consisting of nitrogen, phosphorous and arsenic, comprising a first nitride semiconductor layer made of said III-V group nitride semiconductor layer deposited on a substrate, a second nitride semiconductor layer comprising said III-V group nitride semiconductor layer and a control electrode making Schottky contact with the first nitride semiconductor layer being exposed through removing a portion of the second semiconductor layer.