A fuel cell system comprising: a fuel cell configured to be supplied with a fuel and air to generate an electric power; a combustor configured to combust an off-gas discharged from the fuel cell to produce a combustion discharged gas; a fuel heating part configured to heat the fuel to be supplied to the fuel cell by the combustion discharged gas; an air heating part configured to heat the air to be supplied to the fuel cell by the combustion discharged gas; an anode-side distribution passage configured to distribute the combustion discharged gas to the fuel heating part; a cathode-side distribution passage configured to distribute the combustion discharged gas to the air heating part; and a discharged gas distribution ratio adjustment part configured to adjust a discharged gas distribution ratio, the discharged gas distribution ratio being a ratio of an anode-side combustion discharged gas flow rate to a cathode-side combustion discharged gas flow rate, the anode-side combustion discharged gas flow rate being a flow rate of the combustion discharged gas that flows in the anode-side distribution passage, the cathode-side combustion discharged gas flow rate being a flow rate of the combustion discharged gas that flows in the cathode-side distribution passage, wherein the discharged gas distribution ratio adjustment part is configured to reduce the discharged gas distribution ratio according to an increase in a supply air flow rate as a flow rate of the air to be supplied to the fuel cell.