Method for controlling fuel cell system

A method for controlling a fuel cell system,

• the fuel cell system including
• a fuel cell that includes a solid polymer electrolyte membrane and that generates electric power by causing an electrochemical reaction between a fuel gas and an oxidant gas,
• a fuel gas supply device that supplies the fuel gas into the fuel cell,
• an oxidant gas supply device that supplies the oxidant gas into the fuel cell, and
• an impedance measuring unit that measures an impedance of the fuel cell,
• the method comprising:
• increasing an output electric current of the fuel cell to a required output electric current after continuing generation of electric power at a predetermined threshold electric current value when the impedance measured by the impedance measuring unit is higher than or equal to a predetermined threshold impedance value and the output electric current reaches the predetermined threshold electric current value in a process of increasing the output electric current to the required output electric current.