A power generation cell includes a membrane electrode assembly, with an anode side metal separator and a cathode side metal separator sandwiching the membrane electrode assembly. Flow field walls are provided within the coolant flow field for preventing coolant from flowing into an area corresponding to an oxygen-containing gas inlet buffer, while allowing the coolant to flow into an area corresponding to an oxygen-containing gas outlet buffer. Likewise, flow field walls contact each other for preventing the coolant from flowing into an area corresponding to a fuel gas inlet buffer, while allowing the fuel gas to flow into an area corresponding to a fuel gas outlet buffer.