a piezoelectric actuator sized and configured to expand and contract, the piezoelectric actuator including a plate-shaped piezoelectric ceramic sized and configured to expand and contract when a voltage is applied and a plate-shaped elastic member attached to the piezoelectric ceramic and deformed to have a convex cross-section when the piezoelectric ceramic expands and a concave cross-section when the piezoelectric ceramic contracts;

a shaft axial-movably connected to the piezoelectric actuator;

a moving element mounted to the shaft, the moving element being frictionally displaced relative to the shaft; and

means for amplifying the displacement of the shaft and the moving element, the means being disposed between the piezoelectric actuator and the shaft, the means including a base plate attached to the piezoelectric ceramic, a slanted plate conically extending from the base plate, and a top plate formed at the center of the slanted plate to which the shaft is coupled;

wherein the means for amplifying the displacement is elastically deformed when the piezoelectric actuator expands or contracts to thereby axially move the shaft with an amplified displacement, and

wherein the base plate is deformed to have a convex cross-section when the piezoelectric ceramic expands and a concave cross-section when the piezoelectric ceramic contracts, and

wherein the top plate moves along the axis of the shaft according to the deformation of the base plate.