NOVELTY - A fuel cell comprises a container having a feed port(s) (23) for feeding a mixed gas containing a fuel gas and oxygen to the fuel cell, an exhaust port(s) (25) for discharging an exhaust gas, and a stack of fuel cell components (16) contained in the container. Packing materials are filled in each of the spaces between the feed port, the stack of fuel cell components, and the exhaust port.    USE - Used as fuel cell for power generation.    ADVANTAGE - Electricity can be safely generated in the fuel cell using the mixed fuel gas, having an oxygen concentration falling within the ignition limits for the mixed fuel gas. The performance of the fuel cell is prevented from being lowered due to the carbonization of the fuel in the mixed gas, caused by low concentration of oxygen in the mixed gas, which enhances the power generation efficiency.    DETAILED DESCRIPTION - A fuel cell comprises a container having a feed port(s) and an exhaust port(s), and a stack of fuel cell components contained in the container such that the circumferential faces of the stack of fuel cell components and the inner surfaces of the container are contacted. The fuel cell components comprise a cathode layer (12), an anode layer (14), and an electrolyte layer (10), which is interposed between the cathode and anode layers. A mixed gas containing a fuel gas and oxygen is fed to the fuel cell from the feed port. An exhaust gas is discharged from the exhaust port. Packing materials (24, 26) are filled in each of the spaces between the feed ports, the stack of fuel cell components, and exhaust port. In a gap between the adjacent packing materials, the mixed fuel gas cannot be ignited at the operating condition of the fuel cell even if the mixed fuel gas has an oxygen concentration within the ignition limits for the mixed fuel gas.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic sectional view illustrating the fuel cell.    Electrolyte layer (10)    Cathode layer (12)    Anode layer (14)    Stack of fuel cell components (16)    Feed port (23)    Packing materials (24, 26)    Exhaust port (25)