FUEL CELL SYSTEM

A fuel cell system includes: a fuel cell unit including first to nth fuel cells connected in series to each other to supply electric power to a load device; first to nth supply systems that independently supply cathode gas to the first to nth fuel cells, respectively; a switching device capable of switching a state between a connected state and a disconnected state; and a control unit, when required output to the fuel cell unit is equal to or smaller than a threshold value, configured to control the switching device to switch the state from the connected state to the disconnected state, and to control the first to nth supply systems to respectively control the first to nth fuel cells so as to respectively control flow rates of the cathode gas to be supplied to the first to nth fuel cells.