To provide a piezoelectric actuator whereby impact resistance can be greatly improved without complicating the design or causing a reduction in drive efficiency. When a piezoelectric actuator 31 is incorporated into a main plate 14, an arm part 513 of a vibrator 50 is disposed across from a protrusion 144 via spaces SP1, SP2 having specific dimensions. With the presence of these spaces SP1, SP2, a free end FR moves freely within the spaces SP1, SP2 during driving, but a vibrating part 511 is captured at the free end FR by the protrusion 144 when external impact is applied, and the vibrating part 511 can therefore be prevented from moving beyond the dimensions of the spaces. Resistance against impact from falling can thereby be easily and greatly improved without reducing the drive efficiency, and the usual difficulty of reconciling both drive efficiency and impact resistance can be resolved.