When a microcomputer is automatically reset due to uncontrollable process
and recovers from reset, a cancel pulse signal is outputted from the
microcomputer to a hold circuit to stop supply of a driving current to a
relay. This pulse is generated, when a predetermined condition indicative
of possibility of battery rundown lasts for a predetermined time. The
predetermined condition includes that a hold set condition is detected
based on a status signal inputted from the hold circuit; a card key is
present in a key slot; a key verification inputted from an immobilizer
ECU is not available; a vehicle speed is zero; and an engine revolution
is zero.