A drive apparatus for a piezoelectric actuator prevents locking drive frequency in a state of resonance due to harmonics. There is no need to provide external components to filter, and circuitry can easily be reduced in size. The drive apparatus has a phase difference-DC conversion circuit to detect vibrating state of the vibrating body, a comparison circuit, a harmonics detection circuit to detect that the vibrating body is resonating due to harmonics and outputting a harmonics detection signal, an integration circuit to control the frequency of the drive signal supplied to the piezoelectric element of the vibrating body, a variable frequency oscillation circuit, and a drive circuit. The integration circuit, the variable frequency oscillation circuit, and the drive circuit control the frequency of the drive signal on the basis of the output of the comparison circuit when a harmonics detection signal is not outputted and continue to vary the frequency of the drive signal without controlling the frequency of the drive signal on the basis of the output of the comparison circuit when a harmonics detection signal is being outputted.