A fuel cell system performs control such that when a power requirement for the fuel cell is lower than a predetermined value, a supply of a reaction gas to a fuel cell is stopped to keep an output voltage from the fuel cell equal to a high-potential avoidance voltage that is lower than an open end voltage. The fuel cell system further controls the output voltage from the fuel cell with the high-potential avoidance voltage set to be an upper limit when the power requirement for the fuel cell is equal to or higher than a predetermined value. By setting the upper limit of the output voltage of the fuel cell to be the high-potential avoidance voltage, which is lower than the open end voltage, the catalyst can be inhibited from being degraded by an increase in the output voltage from the fuel cell up to the open end voltage.