A solid oxide fuel cell system is disclosed. The solid oxide fuel cell system includes a cell stack having multiple adjacent fuel cells; a reformer that reforms raw gas and produces fuel gas supplied to the fuel cells; a combustion section that causes combustion of the fuel gas discharged from the fuel cells and heats the reformer with combustion heat of the fuel gas; an ignition device that ignites the combustion section; a combustion state confirmation device that senses that heating of the entire reformer has started using the advancement of flame transfer between fuel cells in the combustion section; and a controller programmed to start an operation of the system heating the reformer by using combustion heat from the combustion section and reaction heat from the partial oxidation reforming reaction (POX) in the reformer. During the period until the combustion state confirmation device senses that the heating of the entire reformer has started after the ignition device ignited the combustion section, the controller suppresses the amount of heat emitted by the partial oxidation reforming reaction in the reformer more than the amount of heat emitted after heating of the entire reformer has started.