A piezoelectric actuator 10 according to each embodiment of the present invention comprises: a column-like piezoelectric body 31, whose bottom face is fixed to a base portion 20, and which stands from the base portion; and a driving power supply section for applying a driving voltage to the piezoelectric body. The piezoelectric body includes two sets (32, 33) of a pair of electrodes for providing electrical fields to the piezoelectric body. The two sets are formed so that each of the two sets is provided to each of two regions into which the piezoelectric body is divided by a virtual plane VPL1 parallel to the center axis CL of the piezoelectric body. The driving power supply section applies the driving voltage Vin having a “frequency between the second-order bending resonant frequency and the first-order expansion-contraction resonant frequency” to either one of the two sets, selectively.