To provide a solid oxide fuel cell device for preventing excess temperature rises inside a fuel cell module during the startup process. During a startup process, a control unit 110 controls the supplied amounts of fuel gas, oxidant gas, and steam supplied to a reformer 20 based on cell stack temperature and reformer temperature and causes transition to a generating process after transitioning to a PDX process, an ATR process, and a SR process, and controls to cause a transition to the next process if in each process the cell stack temperature and reformer temperature meet transition conditions set for each; when control unit 110 determines a temperature rise assist state, it controls to cause a transition to the generating process in a state of reduced fuel gas supply amounts compared to when it does not determine a temperature rise assist state.