To provide a solid oxide fuel cell device capable of stably increasing the temperature of a fuel cell units and smoothly starting electrical generation. The present invention is a solid oxide fuel cell device (1), having a fuel cell module (2); a reformer (20); a fuel supply means (38); a reforming oxidant gas supply means (44); a water supply means (28); a generating oxidant gas supply means (45); and a control section (110) for causing reforming reactions to occur in the reformer at the temperature at which electricity can be generated, prior to the start of electrical generation, in the sequence: POX, in which only the partial oxidation reaction occurs, ATR, in which the partial oxidation reaction and the steam reforming reactions occur, and SR, in which only steam reforming reaction occurs; whereby the control section controls the fuel supply means so that the rate of change in the fuel supply flow rate versus time at the time of transition from the ATR to the SR is the smallest of the rates of change when the fuel supply flow rate is changed at the temperature at which electricity can be generated.