Patent ID: 8283083

Claim:
A fuel cell system comprising: a fuel cell to generate electric power, being supplied with a fuel gas to a fuel electrode thereof and an oxidant gas to an oxidant electrode thereof; a fuel gas supplying device which supplies the fuel gas to the fuel electrode of the fuel cell; an oxidant gas supplying device which supplies the oxidant gas to the oxidant electrode of the fuel cell; a fuel gas pressure detector which detects fuel gas pressure at the fuel electrode of the fuel cell; a fuel gas pressure regulating device which regulates the fuel gas pressure at the fuel electrode of the fuel cell; an exhaust fuel gas discharging device which discharges exhaust fuel gas from the fuel electrode of the fuel cell to the outside, the exhaust fuel gas discharging device including a purge valve; an exhaust fuel gas treatment device which treats the exhaust fuel gas discharged from the purge valve to reduce fuel gas concentration thereof; and a controller which controls power generation of the fuel cell, wherein the controller is programmed to: continue power generation of the fuel cell, control the fuel gas pressure regulating device to lower the fuel gas pressure at the fuel electrode, having the oxidant gas supplying device continue supplying the oxidant gas to the oxidant electrode, and close the purge valve; and after the fuel gas pressure at the fuel electrode becomes equal to or lower than a predetermined negative pressure, stop power generation of the fuel cell and gas treatment of the exhaust fuel gas treatment device.