There are provided a high current semiconductor device that has low on-resistance, high mobility, and good pinch-off characteristics and in which a kink phenomenon is not easily caused even if a drain voltage is increased, and a method for producing the semiconductor device. The semiconductor device of the present invention includes a GaN-based layered body 15 having an opening 28, a regrown layer 27 including a channel, a gate electrode G, a source electrode S, and a drain electrode D. The regrown layer 27 includes an electron transit layer 22 and an electron supply layer 26. The GaN-based layered body includes a p-type GaN layer 6 whose end surface is covered by the regrown layer in the opening, and a p-side electrode 11 that is in ohmic contact with the p-type GaN layer is disposed.