A zero point calibration apparatus for a steering angle sensor using a rotational displacement difference includes: a steering angle sensor configured to sense a steering angle of a column in a steering apparatus for a vehicle; a motor angle sensor configured to sense a rotation angle of a motor which supports steering by the column in the steering apparatus; and a control unit configured to calculate a current rotational displacement difference pattern between the steering angle and the motor angle, and derive the middle point of the current rotational displacement difference pattern. When the middle point does not coincide with a zero point set in the steering angle sensor, the control unit determines that the zero point set in the steering angle sensor is abnormal, and calibrate the zero point.