Fuel cell

A fuel cell has a unit cell whose output is increased. A unit cell (22) of a fuel cell (20) includes a cathode electrode (24) having a gas diffusion layer (6b) and an electrode catalyst layer (28). The electrode catalyst layer (28) is made of carbon black carrying a Pt-Mn-based alloy such as a Pt-Mn alloy on its particle surface. For operating the fuel cell (20) which includes the cathode electrode (24), it is preferable to make the pressure of an oxygen-containing gas supplied to the cathode electrode (24) higher than the pressure of an hydrogen-containing gas supplied to an anode electrode (2) to make the pressure at the cathode electrode (24) higher than the pressure at the anode electrode (2).