To improve an impurity activation rate of a III nitride semiconductor by ion implanting.

When a Ge+ ion is, for example, implanted to the III nitride semiconductor to set an n type, an N+ ion is simultaneously implanted, its surface is covered with an SiO2, and heat-annealed. Thus, a substitution of a Ge atom to a Ga atom position and a suppression of generation of an N vacancy are sufficiently executed, and hence an activity as a toner of an impurity Ge atom can be improved. In order to form a p-type III nitride semiconductor region, an Mg+ ion is, for example, implanted simultaneously with the N+ ion, its surface is covered with the SiO2, and heat annealed.