A vehicular power control system for supplying electric power from a power source of a vehicle to respective ones of a plurality of loads or electronic control units is provided. The vehicular power control system includes a power distribution unit, a customized information storing unit and a power control unit. The power distribution unit receives the electric power and distributes the electric power to a plurality of systems. The customized information storing unit stores customized information in which operation specifications of the plurality of loads or electronic control units are determined. The power control unit controls distribution of electric power to the respective ones of the plurality of loads or electronic control units by the power distribution unit, on the basis of the operation specifications determined in the customized information.