FUEL CELL SYSTEM

A fuel cell system includes: a wetness target value calculating unit configured to calculate a target value of a wet state of the fuel cell; a gas required flow rate calculating unit configured to calculate a cathode gas required flow rate on the basis of a power generation request to the fuel cell; a wetness-control anode gas flow rate calculating unit configured to calculate a wetness-control anode gas circulation flow rate at least on the basis of the wetness target value and the cathode gas required flow rate during a dry control; an anode gas flow rate control unit configured to control an anode gas circulation flow rate on the basis of the wetness-control anode gas circulation flow rate; a wetness-control cathode gas flow rate calculating unit configured to calculate a wetness-control cathode gas flow rate at least on the basis of the wetness target value and a measured value or estimated value of the anode gas circulation flow rate during the dry control; and a cathode gas flow rate control unit configured to control a cathode gas flow rate on the basis of the cathode gas required flow rate and the wetness-control cathode gas flow rate.