To provide a fuel cell that has high generation efficiency, with less energy loss.

This is the fuel cell which is provided with a positive-electrode catalyst layer for reducing oxygen, a negative-electrode catalyst layer for oxidizing fuel, and an electrode-electrolyte integrated material consisting of a solid electrolytic membrane installed between the positive-electrode catalyst layer and the negative-electrode catalyst layer, a mechanism for introducing air to the positive-electrode catalyst layer, and a fuel passage installed, contacting with the negative-electrode for introducing the fuel supplied from a fuel supply part to the negative-electrode catalyst layer, while the fuel passage has a gas discharge port for exhausting the gas existing in the inside to the outside, and has a mechanism for controlling the amount of the gas to be discharged to the outside from the gas discharge port according to the pressure at the gas discharge port.