An electrolyte membrane on the inside of annular frames with an anode-side electrode catalyst layer, a first gas diffusion layer and a first gas flow channel-forming body stacked on top of the membrane. An electrode catalyst layer, a second gas diffusion layer and a second gas flow channel-forming body are stacked on the underside. Frames have a supply channel supplying fuel gas to the gas flow channel in the first gas flow channel-forming body, a discharge channel discharges the fuel gas. An overhang part that extends outward is on the outer peripheral edge of the first channel-forming body to overlap a flange part of the frame beyond the outer peripheral edge of the anode-side electrode catalyst layer. Penetration of seeping water can be prevented by retaining the seeping water in the overhang part.