NOVELTY - A fuel treating apparatus comprises pipe (f1) for taking in modification water and/or source gas, evaporation part for evaporating modification water and mixing source gas with steam, modification part (40) for producing hydrogen mixed gas through mixed source gas using modification catalyst, denaturation part (50, 60) for removing carbon monoxide through hydrogen mixed gas using conversion catalyst, and combustion part (10) for supplying heat to modification part. Each of modification part, evaporation part, and denaturation part encloses cyclically combustion part positioned in the center.    USE - A fuel treating apparatus for supplying hydrogen gas to fuel cell.    ADVANTAGE - Fuel treating apparatus can attach a denaturation part after attaching a pipe.    DETAILED DESCRIPTION - A fuel treating apparatus comprises pipe (f1) for taking in modification water and/or source gas, evaporation part for evaporating modification water and mixing source gas with steam, modification part (40) for producing hydrogen mixed gas through mixed source gas using modification catalyst, denaturation part (50, 60) for removing carbon monoxide through hydrogen mixed gas using conversion catalyst, and combustion part (10) for supplying heat to modification part. Each of modification part, evaporation part, and denaturation part encloses cyclically the combustion part positioned in the center. The pipe is connected with the evaporation part upstream of the evaporation part, and the modification part is connected with the evaporation part downstream of the evaporation part. The denaturation part encloses the evaporation part cyclically and adjoins to the evaporation part. The diameter of innermost of the denaturation part is more than the outermost diameter of the modification part. An INDEPENDENT CLAIM is included for manufacture of a fuel treating apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional diagram of a fuel treating apparatus.    Combustion part (10)    Burner (11)    Modification part (40)    Denaturation part (50, 60)    Pipe (f1)