An on-vehicle controller performs smart control for transmitting a transmission request signal to a predetermined area and for unlocking a door of a vehicle based on a return signal transmitted by a portable device receiving the transmission request signal, security control for providing a warning if improper conduct to the vehicle is detected, remote keyless entry control for locking or unlocking the door according to a manual operation signal, which is transmitted from the portable device according to button manipulation thereof, and immobilizer control for permitting an engine start if an identification code transmitted from a transponder of the portable device coincides with an identification code stored in the vehicle. If a mode switch is switched to an off position, the controller is switched to a power-saving mode for performing only the immobilizer control.