An apparatus of size correction for a hot stamping component is provided. The apparatus includes a jig frame and a plurality of attaching units disposed on the jig frame to rotate in an anteroposterior direction and support a hot stamping component including a quenched component which is partially quenched along the jig frame in the anteroposterior direction. A plurality of clamping units disposed on the jig frame and configured to clamp the hot stamping component. A plurality of measurement units mounted on the jig frame and measure a height of the quenched component based on a predetermined zero base. A plurality of correction units are mounted in front of the jig frame corresponding to the quenched component of the hot stamping component. A force is applied to the quenched component in a vertical direction based on the height size, measured by the measurement unit to adjust the height.