In the annealing step of the method for manufacturing a piezoelectric actuator, the annealing in conducted in two steps: a first annealing step; and a second annealing step conducted at a temperature lower and for a time longer than those of the first annealing step. With such treatment, first, grain growth inside the piezoelectric film can be sufficiently induced, while minimizing the diffusion layer growth, by the first annealing step conducted at a high temperature within a short interval, and then lattice defects in the particles can be sufficiently corrected, while preventing the diffusion layer growth, by the second annealing step conducted at a temperature lower and for a time longer than those of the first annealing step. Accordingly, the piezoelectric characteristic can be improved by sufficiently conducting annealing, while restricting the thickness of the diffusion layer to a range where the piezoelectric characteristic is not affected.