A fuel cell system having a fuel cell includes a power generation-time gas supplier that supplies hydrogen-containing fuel gas to an anode of the fuel cell and supplies an oxygen-containing oxidizing gas to a cathode of the fuel cell during power generation of the fuel cell. The fuel cell system also includes an anode potential rise information acquirer that acquires anode potential rise information, which represents information regarding a status of an anode potential rise of the fuel cell, after termination of supplies of the fuel gas and the oxidizing gas by the power generation-time gas supplier. The fuel cell system further includes an anode morphology variation deriver that derives an anode morphology variation representing a degree of a morphology change of a catalyst metal included in the anode, based on the anode potential rise information.