A fuel cell-battery system includes: a battery module including a battery that stores electric power and a coolant line through which coolant circulates to cool the battery; a fuel cell module including a hydrogen tank that stores hydrogen, a fuel cell that produces the electric power using the hydrogen, and a hydrogen line that connects the hydrogen tank and the fuel cell to deliver the hydrogen from the hydrogen tank to the fuel cell; and a heat exchange module through which the coolant line and the hydrogen line pass such that the coolant is cooled by heat exchange with the hydrogen and the hydrogen is heated by heat exchange with the coolant.