NOVELTY - The fuel reformer useful in fuel cell vehicles, comprises a spraying device (100) to atomize liquid fuel, a reactor (201) reforms the fuel via a catalytic reaction of the atomized fuel, a cooler for cooling ultrasonic sprayer, and a unit for mixing the atomized fuel with open air to supply the reactor. The spraying device comprises the sprayer to atomize the liquid fuel by generating ultrasonic vibrations. The cooler comprises a housing for cooling that accommodates a part of the sprayer, and a unit for supplying a cooling agent to the ultrasonic sprayer through the housing.    USE - Useful to separate hydrogen from the fossil fuel in fuel cell vehicles.    ADVANTAGE - The reformer provides enhanced reforming performances.    DETAILED DESCRIPTION - The fuel reformer useful in fuel cell vehicles, comprises a spraying device (100) to atomize liquid fuel, a reactor (201) reforms the fuel via a catalytic reaction of the atomized fuel, a cooler for cooling ultrasonic sprayer, and a unit for mixing the atomized fuel with open air to supply the reactor. The spraying device comprises the sprayer to atomize the liquid fuel by generating ultrasonic vibrations. The cooler comprises a housing for cooling that accommodates a part of the sprayer, and a unit for supplying a cooling agent to the ultrasonic sprayer through the housing. The ultrasonic sprayer comprises a nozzle end, which discharges sprayed fuel. The housing has an outlet for cooling agent, which conforms to the nozzle end. The cooling agent is air and nitrogen. The reactor is interposed between the spraying device and the reactor. The mixing unit comprises a union pipe. The open air comprises steam or a mixed gas containing steam and air. The liquid fuel comprises water, and the spraying device atomizes the water together with the liquid fuel. INDEPENDENT CLAIMS are included for:    (1) a ultrasonic sprayer for a fuel reformer; and    (2) a fuel reforming method.    DESCRIPTION OF DRAWING(S) - The diagram shows a structure of a fuel reformer:    Spraying device; (100)    Fuel inlet; (111)    Reactor; (200)    Catalyst layer; (201)    Heater/insulator. (202)