A technique for setting offset of a hydraulic pressure sensor which senses operation oil pressure is provided herein. In particular, ignition-off is detected and an ignition-off time point and remaining pressure of the object to be sensed are stored. The remaining pressure is sensed by the hydraulic pressure sensor at the ignition-off time point and stored accordingly. Additionally, whether an ignition is turned on or not after the ignition-off is also detected and an ignition-on time point is stored, when the ignition-on is detected after the ignition-off. A time lapse between the ignition-on from the ignition-off time point is then calculated along with the reduced pressure corresponding to the time lapse due to the time lapse. As a result, a value obtained by subtracting the reduced pressure from the remaining pressure of the hydraulic pressure sensor is set and applied as the offset of the hydraulic pressure sensor.