A fuel cell system includes a first heating mechanism and a second heating mechanism. The first heating mechanism directly heats a reformer using some of an exhaust gas discharged from a fuel cell stack. The second heating mechanism supplies the remaining exhaust gas to a heat exchanger and indirectly heats the reformer by the heat generated in the heat exchanger. The reformer performs preliminary reforming to produce a reformed gas. The reformed gas is supplied to an anode. At the anode, water produced in the power generation is present as a water vapor. The reformed gas is further reformed by steam reforming to produce a hydrogen gas.