To provide a doping method by which stable diffusion excellent in reproducibility can be performed, and diffusion having a uniform in-plane distribution and excellent in controllability can be performed.

A doping method includes the steps of: using carbonate containing a group I element as a constituent element, as a diffusion agent, spraying fine liquid droplets of the solution of the diffusion agent on a ZnO based crystal, and drying the sprayed fine liquid droplets to be firmly fixed, thereby forming a deposition layer of the diffusion agent; and subjecting the ZnO based crystal, on which the deposition layer of the diffusion agent has been formed, to heat treatment and diffusing the group I element in the ZnO based crystal.