To provide a fuel cell device, capable of performing complete combustion through prevention of accidental fire in a combustion chamber, and performing an efficient operation through heat balance.

A reformer, a solid oxide type fuel cell part 5, and a combustion chamber 6 are provided in a container, and reforming at the reformer is carried out with the use of heat obtained by combustion at the combustion chamber 6. The fuel cell part 5 is structured by arraying a plurality of cells 15 in parallel each having a fuel circulating part 13 where reformed gas is circulated and an air circulating part 14 where air is circulated, and the combustion chamber 6 is fitted in adjacency to the fuel cell part 5 as a combustion space for mixing and combusting the reformed gas passing the fuel cell circulating part 13 and the air passing the air circulating part 14. The plurality of cells 15 contain a combustion-priority cell 15a with a ratio of a gas circulation volume of the reformed gas circulating the fuel circulating part 13 to an air circulation volume of the air circulating the air circulating part 14 made larger than that at the other cells 15.