FUEL CELL SYSTEM

The fuel cell system of the present invention comprises: an electric motor, a fuel cell stack, a fuel supply unit, and a controller that controls a power-plant including the fuel cell stack and the fuel supply unit. The controller comprises further: a stack output-response request computing unit to compute a stack output-response request requested for the fuel cell stack; a stack voltage setup unit during idle-stop to set up a lower limit of stack setup-voltage during idle-stop that is set up as a stack voltage during execution of idle-stop so as to be higher as the stack output-response request is larger, and so as to be lower as the request is smaller; and an operation unit of recovering a stack voltage during idle-stop to execute a recovery operation when an actual stack voltage becomes, during execution of idle-stop, lower than the lower limit of stack setup-voltage during idle-stop.