NOVELTY - Fuel storage arranged on anode interior of a fuel cell (12) contains fuel to be supplied to the anode. The fuel storage and fuel cell are contained in a container (18) with cathode on the outer side of the fuel cell. The container is surrounded by a case (30), with a vent hole for supplying air to the cathode. A space is provided between the container and the case, in which the case has a shape adaptable to an electrical device where the power source system (10) is mounted. An electric power storage unit controlled by a control unit (16) stores the electric power generated by the fuel cell.    USE - Power source system for supplying power to an electrical device or use as a power source for automobiles, portable devices, such as cellular phones, notebook type personal computers, personal digital assistants (PDAs), portable music players, digital cameras, electronic dictionaries or books, and other electrical devices such as external chargers for charging cells built in those portable devices.    ADVANTAGE - The space for allowing air circulation is provided between the case and the container to avoid deficiency of air serving as the oxidant for power generation in the fuel cell, allowing the output power of the power source system to be stabilized. By changing the case of the power source system, the power source system is adaptable to a variety of electrical devices. Since the fuel cell and the electric power storage unit are arranged at the corresponding ends of the container interior, heat gradient is generated in the space around the container. Air is confined in the space between the container and the case, facilitating the air supply to the air electrode of the fuel cell. As a result, power generation in the fuel cell can be stabilized for a longer period.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic general configuration diagram of an alternative power source system.    Power source system (10)    Fuel cell (12)    Control unit (16)    Container (18)    Case (30)