A power device manufacturing method is provided. The power device manufacturing method may perform patterning of regions on which a source electrode and a drain electrode are to be formed, may regrow n+-gallium nitride (GaN) and p+-GaN in the patterned regions and thus, a thin film crystal may not be damaged. Also, a doping concentration of n+-GaN or p+-GaN may be adjusted, an ohmic resistance in the source electrode region and the drain electrode region may decrease, and a current density may increase. The power device manufacturing method may regrow n+-GaN and p+-GaN at a high temperature after an n-GaN layer and a p-GaN layer are patterned. Accordingly, a thin film crystal may not be damaged and thus, a reliability may be secured, and an annealing process may not be additionally performed and thus, a process may be simplified and a cost may be reduced.