A lever displacement enlarging mechanism used for an optical stage positioning apparatus and provided with symmetrical levers adapted to transmit on an enlarged scale a displacement force of an actuator element, a distance between a front end of a boundary groove and an outer edge of a connecting column being set shorter than that between a rear end of the boundary groove and the outer edge mentioned above, in such a manner that a fulcrum hinge and a force point hinge are close to the outer edge of the connecting column, whereby a point-of-application hinge is positioned close to the axis of symmetry.
