NOVELTY - The apparatus has a burner waste gas evacuation pipeline (20) for surrounding a circumference of a reformer (10). A carbon monoxide transformer (50) surrounds a reformate gas heat exchanger (40) that is connected to top of a reformate gas evacuation pipeline (11). A reactant preheater (60) is connected to the reformate gas heat exchanger via an outer circumference and an inner circumference of the transformer. A diffusion layer is formed in upper and lower parts of the reformer. Precious metal is dipped on top of the burner wasted gas evacuation pipeline.    USE - Fuel conversion apparatus for a fuel cell system.    ADVANTAGE - The reformer is arranged in an inner side of a burner such that a reformate gas exhaust path is formed through an inner side of reformer, so as to miniaturize the apparatus. The apparatus removes the burner waste gas in harmful material, increases waste-heat recovery amount of the burner wasted gas, activates the reforming catalyst, saves energy, and increases the efficiency of the burner by preheating the fuel. The apparatus prevents the efficiency decrease phenomenon of the reforming catalyst even when the waste-heat recovery amount and burner efficiency of the burner wasted gas are increased, avoids separate supply requirement of additional fuel to the burner, prevents the overheat of transformer, maintains steam/carbon ratio, improves the working efficiency, and maintains optimal temperature without a separate chiller such as fan. The apparatus maintains reforming performance steadily, and improves durability of the reforming catalyst. The apparatus can be operated in a stable manner even when a separate control logic is not used.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a fuel conversion apparatus.    Reformer (10)    Reformate gas evacuation pipeline (11)    Burner waste gas evacuation pipeline (20)    Reformate gas heat exchanger (40)    Carbon monoxide transformer (50)    Reactant preheater (60)