A piezoelectric resonator that includes a single crystal Si layer, a piezoelectric thin film formed from aluminum nitride and provided on the single crystal Si layer, and first and second electrodes provided so as to sandwich the piezoelectric thin film. An element excluding nitrogen and aluminum is doped into the piezoelectric thin film formed from aluminum nitride, and a synthetic acoustic velocity of portions of the piezoelectric resonator other than the single crystal Si layer substantially coincide with the acoustic velocity of the single crystal Si layer.