A secondary battery charging system, mounted on a vehicle having an internal combustion engine, has a secondary battery, a fuel cell, a fuel storage unit, and a fuel supply controller. In order to start the engine of the vehicle, the engine requires the electric power from the secondary battery. The fuel storage unit stores a fuel to be supplied to the fuel cell. When a given condition is satisfied, the fuel supply controller instructs the fuel storage unit to supply the fuel to the fuel cell in order to start the operation of the engine of the vehicle. The fuel cell thereby starts the generation of the electric power by performing electric chemical reaction and supplies the generated electric power to the secondary battery. The secondary battery supplies the electric power to the engine of the vehicle. The engine initiates its operation.