A high-temperature fuel cell system includes a fuel cell that includes an anode and a cathode and that generates power by using a fuel gas and an oxidant gas, a fuel-gas path along which the fuel gas flows, an oxidant-gas path along which the oxidant gas flows, an anode-off-gas path along which an anode off-gas flows, a cathode-off-gas path along which a cathode off-gas flows, a combustion space in communication with the anode-off-gas path and the cathode-off-gas path and in which the anode off-gas and the cathode off-gas are burned, a flue-gas path along which a flue gas flows, a cathode-off-gas branch portion disposed on the cathode-off-gas path between the combustion space and the cathode and at which some of the cathode off-gas is branched from the cathode-off-gas path, and a first heat exchanger that enables heat exchange between the oxidant gas, the flue gas, and the cathode off-gas.