NOVELTY - The fuel cell (FC) has a frame (4) is arranged on an outer periphery portion of membrane electrode assembly (M), and a separator (5) defines a gas flow channel (G) between electrode assembly and frame. A diffuser portion (D) is a portion of gas flow channel formed between separator and frame. An electrode layer (1) is comprised of a metal porous portion (23,33) that is an electrode surface layer and has gas permeability. The metal porous portion is provided with an end portion and extension portion (23A,33A) for covering a region corresponding to the diffuser portion of the frame.    USE - Fuel cell such as polymer electrolyte fuel cell (PEPC) of fuel cell stack (claimed) for power source mounted in vehicle.    ADVANTAGE - Stress applied to the electrolyte membrane can be reduced using rigidity of metal porous portions. The fuel cell can prevent the frame from deforming, and avoids stress concentration of the electrolyte membrane in gaps between carbon porous portions and the frame. The damage of electrolyte membrane can be prevented and realizes increase of endurance. Since the stress of the electrolyte membrane is reduced and the endurance of the electrolyte membrane is increased, the fuel cell stack can enhance the reliability. Each fuel cell can be made thinner to realize small and lightweight fuel cell stack. The fuel cell can prevent the frame from deforming, and avoids stress concentration of electrolyte membrane in gaps between first carbon porous portions and frame even when differential pressure between cathode side and anode side. Since the frame and the metal porous portions are integrated, assembly accuracy can be increased, productivity can be increased and manufacturing cost can be reduced.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for fuel cell stack.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the essential portions of fuel cell.    Electrode layer (1)    Frame (4)    Separator (5)    Metal porous portions (23,33)    Extension portions (23A,33A)    Diffuser portion (D)    Fuel cell (FC)    Gas flow channel (G)    Membrane electrode assembly (M)