A fuel cell system comprising: a fuel cell; a fuel processing unit disposed in an anode gas passage of the fuel cell and configured to process a raw fuel for the fuel cell; an oxidant gas heating unit disposed in a cathode gas passage of the fuel cell and configured to heat an oxidant gas for the fuel cell; a combustor configured to combust the raw fuel and disposed to be capable of heating the fuel processing unit and the oxidant gas heating unit by a combustion gas of the raw fuel; a supply control unit configured to, during a warm-up of the fuel cell, control supply of the raw fuel to the fuel processing unit and the combustor; and a power generation control unit configured to control a power generation state during the warm-up of the fuel cell, wherein the power generation control unit is configured to cause the fuel cell to perform power generation when the fuel cell has reached a power generation available temperature, and wherein: the supply control unit includes a warm-up target flow rate setting unit configured to set a warm-up target flow rate according to a temperature of the fuel cell as a target flow rate of the raw fuel during the warm-up of the fuel cell; and the supply control unit is configured to, when the fuel cell has reached the power generation available temperature, supply the raw fuel of the warm-up target flow rate to the fuel processing unit and the combustor in a divided manner, characterized in that the warm-up target flow rate is greater than a supply flow rate of the raw fuel in a rated operation after the warm-up. a fuel cell; a fuel processing unit disposed in an anode gas passage of the fuel cell and configured to process a raw fuel for the fuel cell; an oxidant gas heating unit disposed in a cathode gas passage of the fuel cell and configured to heat an oxidant gas for the fuel cell; a combustor configured to combust the raw fuel and disposed to be capable of heating the fuel processing unit and the oxidant gas heating unit by a combustion gas of the raw fuel; a supply control unit configured to, during a warm-up of the fuel cell, control supply of the raw fuel to the fuel processing unit and the combustor; and a power generation control unit configured to control a power generation state during the warm-up of the fuel cell, wherein the power generation control unit is configured to cause the fuel cell to perform power generation when the fuel cell has reached a power generation available temperature, and wherein: the supply control unit includes a warm-up target flow rate setting unit configured to set a warm-up target flow rate according to a temperature of the fuel cell as a target flow rate of the raw fuel during the warm-up of the fuel cell; and the supply control unit is configured to, when the fuel cell has reached the power generation available temperature, supply the raw fuel of the warm-up target flow rate to the fuel processing unit and the combustor in a divided manner, characterized in that the warm-up target flow rate is greater than a supply flow rate of the raw fuel in a rated operation after the warm-up. the supply control unit includes a warm-up target flow rate setting unit configured to set a warm-up target flow rate according to a temperature of the fuel cell as a target flow rate of the raw fuel during the warm-up of the fuel cell; and the supply control unit is configured to, when the fuel cell has reached the power generation available temperature, supply the raw fuel of the warm-up target flow rate to the fuel processing unit and the combustor in a divided manner, characterized in that the warm-up target flow rate is greater than a supply flow rate of the raw fuel in a rated operation after the warm-up.