PURPOSE: To enlarge a displacement by several to several ten times for practical use by combining a piezo-electric actuator and a buckling spring to enlarge the actuator produced displacement by the buckling spring.

CONSTITUTION: A stage 1 is provided in the conters between both sides with projections 9 for receiving springs to be pressed from both sides by leaf springs 4, 5. The spring 5 is fixedly embedded in a frame 2 on one end and compressed on the other end by a headless screw. The frame 2 is also provided with projections opposed to those on the stage 1 and the leaf springs 4, 5 are sandwiched between the projections. Also, since the leaf springs are pressed by said projections on the frame 2 to be always warped, the spring 5 is subjected to the buckling defromation by tightening a screw 8 to move the stage 1 to the right side. When voltage is applied to an actuator 6, the leaf spring 4 is buckled and deformed according to the the size of applied voltage to push back the stage 1 to the left side. The relationship between the applied voltage and piezo-electric actuator 6 displacement is shown by the saturation curve while, more linearity relationship is maintained by utilizing the balance of springs.