Fuel cell system

A recirculation device (9) recirculates gas discharged from a combustor (3), through a recirculation passage (4) and a reformer (1), and a supply device (17) supplies fuel and water/air to the reformer. A controller (15) controls supply device to stop fuel and water/air supplied to the reformer, and recirculation device to recirculate the discharged gas, in stop mode of the fuel cell system. An independent claim is also included for control method of fuel cell system.