A fuel cell system includes a fuel cell that generates electric power using fuel gas and oxidant gas, a fuel gas supply path through which the fuel gas is supplied to an anode inlet of the fuel cell, a recycle gas path through which anode off-gas discharged from an anode outlet of the fuel cell returns to the fuel gas supply path, and a pressure booster arranged in the recycle gas path, and the pressure booster is arranged above a confluence portion where the fuel gas supply path and the recycle gas path meet each other when gravity acts downward from above.