NOVELTY - Fuel reformer has modifier (1) for modifying desulfurized original hydrocarbon fuel. Reformer has normal temperature desulfurizer (7) and deoxidation device (8) to remove sulfur compound and oxygen, respectively contained in original fuel supply line, and are provided sequentially to hydrodesulfurization device. Fuel reformer forms hydrogen rich reformed gas, and recycles portion of reformed gas.    USE - For fuel cell power generating device (claimed).    ADVANTAGE - The fuel cell power generating device utilizing the fuel reformer has simple system and reduced degradation of catalyst, and has enhanced life cycle.    DETAILED DESCRIPTION - A fuel reformer comprises a modifier for modifying desulfurized original fuel comprising hydrocarbon fuel, such as town gas containing trace amount of sulfur compound and trace amount of oxygen, as original fuel. The reformer has a normal temperature desulfurizer and a deoxidation device for removing sulfur compound and oxygen, respectively contained in the original fuel supply line. The normal temperature desulfurizer and the deoxidation device are provided sequentially to a hydrodesulfurization device. The recycled reformed gas is supplied between the normal temperature desulfurizer and the deoxidation device. The fuel reformer forms a hydrogen rich reformed gas, and recycles a portion of the reformed gas. The recycled reformed gas is supplied to a hydrodesulfurization device (2) as additional hydrogen for hydrodesulfurization machines. The original fuel supply line introduces the original fuel into a field fuel.    INDEPENDENT CLAIMS are also included for the following:    (i) operating method of fuel reformer comprising desulfurizing fuel reformer with the normal temperature desulfurizer, recycling reformed gas at regular driving transfer, and desulfurizing the reformed gas by the normal temperature desulfurizer and the hydrodesulfurization device;    (ii) fuel cell power generating device, which generates electricity using the reformed gas obtained by the fuel reformer.    DESCRIPTION OF DRAWING(S) - The figure shows the outline system systematic diagram of fuel reformer. (Drawing includes non-English language text.)    Modifier (1)    Hydrodesulfurization device (2)    Normal temperature desulfurizer (7)    Deoxidation device (8)