<p>A semiconductor device is provided with an undoped GaN layer (103) formed on a substrate (101); an undoped AlGaN layer (104), which is formed on the undoped GaN layer (103) and has band gap energy larger than that of the undoped GaN layer (103); a p-type AlGaN layer (105) and a high-concentration p-type GaN layer (106), which are formed on the undoped AlGaN layer (104); and an n-type AlGaN layer (107) formed on the high-concentration p-type GaN layer (106). On a region exposed from an opening section (107a) formed on the n-type AlGaN layer (107) on the high-concentration p-type GaN layer (106), a gate electrode (112) brought into ohmic contact with the high-concentration p-type GaN layer (106) is formed.</p>
