An electrostriction actuator comprises upper and lower electrostriction boards, having electrodes individually on either side thereof, and a conductive shim interposed between the inside electrodes. The actuator has a fixed end at one end thereof and a free end for bending movement at the other end. An amplifier for supplying driving voltage to the actuator is an inverted amplifier, whose output terminal is connected to the shim, so that an output voltage is supplied to the inside electrodes. The outside electrode of the upper electrostriction board is connected to a power source (not shown) for supplying constant voltage to the amplifier, and the outside electrode of the lower electrostriction board is connected to a power source (not shown) for supplying constant voltage to the amplifier.