Patent ID: 8691460

Claim:
A method of stopping an operation of a fuel cell system having a fuel cell to generate power according to an electrochemical reaction of an oxide gas supplied to a cathode side of an electrolyte membrane/electrode assembly with a fuel gas supplied to an anode side of the electrolyte membrane/electrode assembly, an oxide-gas supply apparatus to supply the oxide gas to the fuel cell, a fuel-gas supply apparatus to supply the fuel gas to the fuel cell, and a gas replacement apparatus to supply a replacement gas to the anode side of the fuel cell to replace the fuel gas on the anode side with the replacement gas, the method comprising: an in-stop-mode power generating process of, if an instruction to stop an operation of the fuel cell is detected, stopping supply of the fuel gas, supplying the oxide gas to the fuel cell to generate power from the oxide-gas supply apparatus, and stopping power generation of the fuel cell; a determination process of determining whether or not the power generating process in the stop mode is executed; and a gas replacing process of, after the power generation of the fuel cell is stopped, activating the gas replacement apparatus at a predetermined timing to supply a replacement gas to the anode side of the fuel cell to replace the fuel gas on the anode side with the replacement gas, wherein, in a case in which the determination process determines that the power generating process in the stop mode is executed, the gas replacing process is executed at a timing later than a case in which the determination process determines that the power generating process in the stop mode is not executed.