The fuel cell system includes a hydro-desulfurizer that removes a sulfur compound in raw material gas; a raw material gas heating unit that heats raw material gas before the raw material gas enters the hydro-desulfurizer; a reformer that generates reformed gas using the raw material gas that has passed through the hydro-desulfurizer; a fuel cell that generates electric power using the reformed gas from the reformer as fuel; a combustor that combusts fuel unused in the fuel cell; an exhaust gas channel through which exhaust gas generated in the combustor flows; and a housing that is provided in a part of the exhaust gas channel and houses the raw material gas heating unit and the hydro-desulfurizer, in which exhaust gas flowing through the housing undergoes heat exchange with the raw material gas heating unit and the hydro-desulfurizer.