FUEL CELL SYSTEM

The present invention provides a fuel cell system which can inhibit a problem that leakage of electricity is determined when a fuel cell is started even if the stopped state of a pump that circulatesa refrigerant that cools the fuel cell continues for a long time. The fuel cell system includes: a fuel cell; a circulation path configured to circulate a coolant that cools the fuel cell; a pump thatis provided at the circulation path and that causes the coolant to circulate; a radiator that is provided at the circulation path and the dissipates heat from the coolant; an ion exchanger that is provided at a circulation path and that restores insulation resistance of a coolant; a detector that is provided at the circulation path and that detects conductivity of the coolant; and a controller that is electrically connected to the detector and the pump and that controls driving of at least the pump. In a state in which the pump is stopped and in a case in which the insulation resistance of the coolant, which is obtain