This fuel cell system is provided with: a fuel cell; a fuel processing unit which processes a crude fuel and produces a fuel gas for the fuel cell; an oxidant gas heating unit which heats an oxidant gas for the fuel cell; a combustor which combusts the crude fuel and produces a combustion gas for heating the fuel processing unit and the oxidant gas heating unit; and a control unit which controls the supply of the crude fuel to the fuel processing unit and to the combustor during the warm-up period of the fuel cell. The control unit supplies the crude fuel to both the fuel processing unit and the combustor in cases where the fuel processing unit is within the operable temperature range thereof.