PURPOSE: To reduce the possibility of vehicle barglary while maintaining safety of an ECU by obstructing start of the vehicle when collated identification codes are not conforming to a prescribed combination, and renewing the identification codes of first and second control units to new combinations after starting a power device.

CONSTITUTION: When an ignition switch is changed from the ON position to the OFF position, a collating means collates an identification code stored in a first control unit 21 with an identification code stored in a second control unit 22. When the collated identification codes are not conforming to a prescribed combination, a start preventing means 27 obstructs start of the vehicle. After starting a power device, these identification codes are renewed to new combinations by a renewal means 23, and these identification codes are stored in the memory devices of the respective control units 21, 22. Hereby the possibility of vehicle barglary can be remarkably reduced.