A vehicle includes a battery and an alternator as a power source, and a plurality of vehicle load groups that operate commonly receiving power supply from the power source. When a plurality of requests for actuating the plurality of loads are made simultaneously, a control circuit determines a request of higher priority and a request of lower priority based on a predetermined priority for each of said requests. The control circuit operates the corresponding load as requested in response to the request of high priority, and operates the corresponding load with the operation limited to consume smaller power than requested in response to the request of low priority. More preferably, one of the plurality of loads is variable valve timing apparatus changing a timing of opening/closing an intake valve or an exhaust valve of an internal combustion engine.