A caliper unit may include a piston configured to linearly reciprocate in a cylinder, a pushrod configured to move along with the piston, an operating ramp configured to linearly move the pushrod in one direction, a high compression spring supported by the cylinder and configured to restore the pushrod to an original position, and a floating ramp interposed between the high compression spring and the operating ramp to transfer elastic force of the high compression spring to the operating ramp.