Processing method for fuel cell system, component detaching method, and fuel cell system

A fuel cell system comprising:

• a fuel cell stack configured to generate electric power when supplied with an anode gas and a cathode gas;
• an anode gas supply unit configured to supply the anode gas to the fuel cell stack;
• a cathode gas supply unit configured to supply the cathode gas to the fuel cell stack;
• a voltage measuring unit configured to measure a voltage of the fuel cell stack;
• an inert gas supply unit configured to supply an inert gas to an anode of the fuel cell stack;
• and
• a control unit configured to perform a process of discharging the anode gas from an inside of the fuel cell system to an outside of the fuel cell system,
• wherein the control unit is configured, in a state in which the fuel cell stack is not supplied with the anode gas and the cathode gas and generation of electric power in the fuel cell stack is stopped, to cause the cathode gas supply unit to start supply of the cathode gas to the fuel cell stack,
• to cause the inert gas supply unit to start supply of the inert gas to the anode of the fuel cell stack when the voltage detected by the voltage measuring unit increases and then becomes equal to or less than a predetermined first voltage after the supply of the cathode gas has been started, and
• to cause the inert gas supply unit to stop the supply of the inert gas when the voltage measured by the voltage measuring unit increases and then becomes equal to or less than a predetermined second voltage after the supply of the inert gas has been started.