A piezoelectric ceramic base member is formed of a bar shaped bismuth layer compound, and has main electrodes on two end surfaces in an oscillation direction, with connection electrodes at side-surface central portions of the piezoelectric ceramic base member electrically connected to the main electrodes through extraction conductors interposed therebetween, respectively. The oscillation and polarization directions are set in the same direction, and the piezoelectric ceramic base member is driven at a resonant frequency or at a frequency in the vicinity thereof. The crystal c axis is preferably oriented in a direction orthogonal to the polarization direction. The resonant actuator is able to obtain a high oscillation speed as it has a large mechanical quality factor Qm, and the oscillation is not disturbed by mechanical factors.