Abstract: A control unit of a fuel cell system measures or estimates an amount of nitrogen in an anode flow field, performs a first comparison by comparing the amount of nitrogen with the first threshold amount, performs a second comparison by comparing a differential pressure calculated by subtracting a cathode pressure value indicating a pressure inside a cathode flow field from an anode pressure value indicating a pressure inside the anode flow field with the second threshold pressure when the amount of nitrogen in the anode flow field is greater than the first threshold amount in the first comparison, and controls opening and closing of a valve based on the result of the first comparison and the result of the second comparison.

Abstract: A control unit of a fuel cell system estimates an amount of nitrogen in an anode flow field, performs a first comparison by comparing the estimated amount of nitrogen with a first threshold amount, performs a second comparison by comparing a target power generation amount as a target amount of power generation by a fuel cell stack with a second threshold amount in a case where the estimated amount of nitrogen in the anode flow field exceeds the first threshold amount in the first comparison, and controls opening and closing of a first valve and opening and closing of the second valve based on a result of the first comparison and a result of the second comparison.

Abstract: A control unit of a fuel cell system opens a second valve at the time of closing a first valve, and maintains the same operating state of a compressor before closing the first valve and after opening the second valve.