PURPOSE: To contrive to miniaturize a device and to prevent a reforming catalyst from being damaged by heat, by forming a reaction gas channel and a combustion gas channel through heat transfer surfaces and supporting a catalyst on the heat transfer surfaces.

CONSTITUTION: A fuel reformer alternately consists of a channel 53 in which a reaction gas (process gas) flows as reaction parts and a gas channel 55 in which a combustion gas flows as heating parts. A wall dividing the gas channel 53 from the gas channel 55 constitutes heat transfer surfaces 41. The process gas flows through the heat transfer surfaces 41 from the bottom to the top and fuel, air and the combustion gas flow from the top to the bottom. A unit consisting of the plural reaction parts alternately made of the plural heat transfer surfaces 41 and the outer heating parts is supported by side plates 51 from both sides. The side plates 51 are fixed by a fastening bolt 52. A reforming catalyst 24 is supported on the heat transfer surfaces 41 at the side of the reaction parts 53 in which the process gas (reformed gas) flows. On the other hand a combustion catalyst 28 is supported at the other heating parts 55 in which the combustion gas flows.