A polymer electrolyte fuel cell comprises an electrolyte membrane-electrode assembly, a pair of conductive separator plates sandwiching the electrolyte membrane of the electrolyte membrane-electrode assembly, and a pair of sealing means sealing between the electrodes of the electrolyte membrane-electrode assembly and the separator plates. The pair of sealing means is constituted by combination of a flat sealing member having a flat portion in flat contact with the electrolyte membrane and of a linear sealing member having a rib in linear contact with the electrolyte membrane, and at least part of the rib is in the form of falling in the direction to the electrode when the electrolyte membrane, the pair of electrodes and the pair of separator plates are stacked to be cramped. This makes it possible for the fuel cell to have an excellent sealing property and a stable output characteristic.