FUEL CELL SYSTEM

A fuel cell system, including: an electric power generation control unit; an insulation-resistance measurement signal generation unit configured to generate a voltage-divided AC signal obtained by dividing an amplitude of a measurement AC signal; and an insulation resistance measurement unit configured to measure a resistance value of the insulation resistance, in which when the insulation resistance measurement unit detects, in a state where a voltage is maintained during an intermittent operation of the electric power generation control unit, an excessive noise state indicating a change in which a range of fluctuations of the peak value of the voltage-divided AC signal exceeds a predetermined allowable range of fluctuations, the insulation resistance measurement unit instructs the electric power generation control unit to change a fluctuation frequency of an output voltage of the fuel cell from a current frequency and then measures the resistance value of the insulation resistance.