A fuel cell system (101) is comprised of a power generating portion (5) having a plurality of laminated cells; a fuel supply portion (4) for supplying fuel to the cells, which can adjust the amount of fuel to be supplied; a voltage monitoring portion (8) for monitoring the output voltage of at least one specific cell (51) selected among the plural cells; a power supply portion (13) for temporarily supplying electric power to the specific cell; and a control portion (9) which detects a voltage difference between the minimum value of the output voltage occurring after electric power is supplied to the specific cell and the response value of the output voltage after the output voltage is reduced to the minimum value, and which controls the amount of fuel to be supplied in accordance with the voltage difference.
