TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Device: In the solid oxide fuel cell device, the controller controls the water supply device so that electrical generation is started after the water supply flow rate is reduced during the SR operation and prior to the startup of electrical generation. The controller controls the electrical generation oxidant gas supply device so that electrical generation is started after the electrical generation oxidant gas supply flow rate is reduced during the SR operation and prior to the startup of electrical generation. The fuel cell module is constituted to output variable electrical power in a predetermined output power range, and the controller controls the fuel supply device so that the fuel supply flow rate reduced prior to startup of electrical generation during the SR operation is more than the fuel supply flow rate corresponding to the minimum output power, where the controller controls the fuel supply device so that the fuel supply flow rate reduced prior to startup of electrical generation during the SR operation is fixed at a predetermined value which is greater than the fuel supply flow rate corresponding to the minimum output power. Also, the controller controls the fuel supply device so that the fuel supply flow rate reduced prior to startup of electrical generation during the SR operation is fixed at a predetermined value which is greater than the fuel supply flow rate corresponding to an intermediate value in the output power range. The controller controls the fuel supply device so that the fuel supply flow rate reduced prior to startup of electrical generation during the SR operation is fixed at a value corresponding to approximately the maximum value in the output power range. The controller controls the fuel supply device, the water supply device, and the electrical generation oxidant gas supply device so that the proportions of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate immediately prior to the start of electrical generation are set to predetermined electrical generation standby supply proportions which are different from the proportions of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate during electrical generation, where the electrical generation standby supply proportions are configured so that the proportion of the fuel supply flow rate within the entirety of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate is smaller than the proportion of the fuel supply flow rate within the entirety of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate when generating electricity. The electrical generation standby supply proportions are configured so that the proportion of the electrical generation oxidant gas supply flow rate within the entirety of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate is greater than the proportion of the electrical generation oxidant gas supply flow rate within the entirety of the fuel supply flow rate, the water supply flow rate, and the electrical generation oxidant gas supply flow rate when generating electricity. Alternatively, the solid oxide fuel cell device for generating electricity by reacting fuel and electrical generation oxidant gas comprises: a fuel cell module furnished with multiple solid oxide fuel cell units; fuel supply means for supplying fuel used to generate electricity; a reformer for reforming fuel supplied from the fuel supply means and supplying the reformed fuel to the solid oxide fuel cell units, disposed above the solid oxide fuel cell units so as to be heated when fuel not used to generate electricity in the solid oxide fuel cell units is combusted at the top end of the solid oxide fuel cell units; water supply means for supplying water to the reformer; electrical generation oxidant gas supply means for supplying oxidant gas for electrical generation to the solid oxide fuel cell units; and control means for controlling the fuel supply means and the water supply means during startup procedure where the solid oxide fuel cell units in the fuel cell module are raised to a temperature at which electricity can be generated, carrying out within the reformer the SR operation, which consists of only the steam reforming reaction, then starting the generation of electricity; where the control means controls the fuel supply means to reduce the fuel supply flow rate during the SR operation prior to the start of electrical generation, then starts the generation of electricity.