NOVELTY - The system has a control unit that determines the electric power sharing ratio and controls a power distributing device (104). The system region that supplies electric power to an electrical load is divided into low, middle, and high output regions, of which system output is frequent in the middle output region. In the middle output region, the electric power of a fuel cell (101) follows the power to be supplied to the load. In the low and high output regions, the electric power of a battery (102) follows the power to be supplied to the load.    USE - Electric power supply system.    ADVANTAGE - Enables the provision of an electric power supply system that prevents an excess of electricity discharged by the fuel cell, since the system efficiently generates by setting the following lower limit value of the fuel cell in accordance with the change in the efficiency of the output electric power of the fuel cell in operation. The electric power supply system can prevent the remaining capacity of the electricity storage device from reducing radically by raising the following upper limit value in accordance with the remaining capacity of the electricity storage device, increasing the output electric power of the fuel cell. The system can determine the distribution of the output electric power so as to increase and reduce the output electric power supplied by the electric power generator in accordance with the change of the output electric power value required for the electric power supply system, in which the output frequency is equal to or higher than a predetermined value in the frequency distribution of the output electric power, and can determine the distribution of the output electric power so as to increase the output electric power supplied by the electricity storage device, in the assist region in which the output frequency is lower than a predetermined value in the frequency distribution, and accordingly can prevent the excess of discharging from the electricity storage device.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of fuel cell system.    Fuel cell (101)    Battery (102)    Power distributing device (104)    Motor (107)    Motor control unit (108)