FUEL CELL SYSTEM

During startup of a fuel cell system, a control device adjusts opening degrees of a bypass valve, an inlet side stop valve, and an outlet side stop valve in a manner that the flow rate of an oxygen-containing gas in a bypass channel supplied from an oxygen-containing gas supply apparatus becomes larger than the flow rate in an oxygen-containing gas supply channel and an oxygen-containing off gas discharge channel. In this manner, during startup of the fuel cell system, while diluting concentration of a fuel gas remaining at a cathode of the fuel cell stack, the fuel gas is discharged to the outside in a short period of time.