A catalyst deterioration recovery device in a fuel cell system that includes a fuel cell including a membrane electrode assembly configured to include an electrolyte membrane and anode and cathode catalysts between which the electrolyte membrane is sandwiched from both sides and anode and cathode separators respectively including an anode gas flow channel and a cathode gas flow channel, the membrane electrode assembly being sandwiched between the anode and cathode separators. The catalyst deterioration recovery device recovers performance decreased by adsorption of carbon monoxide to the anode catalyst. The catalyst deterioration recovery device includes a recovery control unit configured to supply at least a part of oxygen to be supplied to the cathode gas flow channel to the anode catalyst via the electrolyte membrane.