It is an object to provide a simple fuel cell system and to provide a fuel cell system capable of reducing the amount of consumption of fuel gas at the time of completion of operation. A fuel cell system includes a supply piping from a fuel gas supply source storing fuel gas to a gas inlet of a fuel cell and a circulation piping from a gas outlet of the fuel cell to a junction at which the circulation piping joins the supply piping. A regulating valve and a shut-off valve are disposed on the upstream side of the junction in the supply piping. A portion on the downstream side of the junction in the supply piping and the circulation piping are in constant communicated.
