To provide a fuel cell device capable of extending the years of service life of a reformer by suppressing thermal runaways. The present invention is a solid oxide fuel cell device (1), including a fuel cell module (2) having multiple fuel cell units (16); a reformer (20b) disposed above the fuel cell units, for producing hydrogen by a partial oxidation reforming reaction and a steam reforming reaction; a vaporizing chamber (20a) disposed adjacent to the reformer; a combustion chamber (18) for heating the vaporization chamber; a water supply device; a supply device for oxidant gas for electrical generation; and a controller (110) for raising the fuel cell unit to a temperature at which electrical generation is possible; wherein fuel electrodes in each individual fuel cell unit are constituted to act as catalysts for a shift reaction, and the controller executes only the ATR step and SR step in the reformer.