FUEL CELL SYSTEM

A fuel cell system 100 comprises a fuel cell chamber R1 which is provided in an indoor place and accommodates the housing 10a which accommodates the fuel cell 34 and the combustion unit 36, a ventilation exhaust line KL which includes an intake unit 10c introducing air into the fuel cell chamber and an exhaust unit 10d discharging the air to the outdoor place, a first fan 42 which is provided at the exhaust unit to discharge air from the fuel cell chamber, and a check valve 41 which is provided at the intake unit and configured to suppress the circulation of the air into the fuel cell chamber from the outside thereof in a normal state and to allow the circulation of the air while being opened when the inside of the fuel cell chamber becomes a negative pressure state.