FUEL CELL SYSTEM

The fuel cell system includes a fuel cell stack, a humidifier provided on an oxygen-containing gas supply flow path to humidify an oxygen-containing gas flowing through the oxygen-containing gas supply flow path, a discharge path stop valve provided on an oxygen-containing gas discharge flow path and configured to be opened during power generation by the fuel cell stack, and a pressure regulator provided downstream of the discharge path stop valve to regulate pressure so that it is higher on the upstream side than the downstream side.