Fuel cell system

A fuel cell system, comprising:

• a fuel cell;
• an electric power generation control unit configured to control an amount of electric power generated by the fuel cell by controlling an amount of oxidant gas and fuel gas supplied to the fuel cell;
• 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 using a resistance voltage divided by an insulation resistance between an outer conductor located around a high voltage circuit including the fuel cell and the high voltage circuit, and a reference resistance having a known resistance value;
• and
• an insulation resistance measurement unit configured to measure a resistance value of the insulation resistance based on a peak value of the voltage-divided AC signal, wherein
• 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.