A polymer electrolyte fuel cell of the present invention includes a hydrogen ion-conductive polymer electrolyte membrane, an anode and a cathode sandwiching the hydrogen ion-conductive polymer electrolyte membrane, an anode-side conductive separator plate having a gas flow channel for supplying a fuel gas to the anode, and a cathode-side conductive separator plate having a gas flow channel for supplying an oxidant gas to the cathode. Each of the anode-side conductive separator plate and the cathode-side conductive separator plate is rectangle in shape and has an oxidant gas manifold aperture for an inlet arranged on one short side thereof, an oxidant gas manifold aperture for an outlet arranged on the other short side thereof, a fuel gas manifold aperture for an inlet and a fuel gas manifold aperture for an outlet arranged on different longitudinal sides thereof, and a cooling water manifold aperture for an inlet and a cooling water manifold aperture for an outlet arranged on the different longitudinal sides thereof. The respective fuel gas manifold apertures are disposed opposite to the cooling water manifold apertures. The oxidant gas manifold apertures, the fuel gas manifold apertures, and the cooling water manifold apertures have openings of different shapes.