NOVELTY - A fuel reformer (10) consists of a modification portion (11) which modifies a fuel by catalytic reaction to produce hydrogen, a fuel supplier (12), and an air supplier (13). The modification portion is provided with catalytic converter (11A) containing a combustion catalyst supported by support (I), and catalytic converter (11B) containing a modification catalyst supported by support (II) and provided at the downstream of catalytic converter (11A). The fuel reformer is driven in a high-pressure state than atmospheric pressure.    USE - Fuel reformer is used for manufacturing hydrogen in gasoline and diesel internal combustion engines.    ADVANTAGE - The fuel reformer has a simple structure, and enables efficient modification of fuel by catalytic reaction to stably produce hydrogen. Since oxygen is utilized in the combustion catalyst arranged upstream of the modification catalyst, oxygen concentration of the upstream edge portion of modification catalyst is reduced and generation of local high-temperature region in the upstream edge portion is prevented. Hence, thermal deterioration by sintering of modification catalyst is suppressed and durability of modification catalyst is improved. Modification reaction can be easily controlled, as a result of the combustion catalyst being buffered and being able to absorb the fluctuation amount of fuel gas introduced. When the reaction temperature of modification catalyst falls, the selection freedom degree of catalyst is improved. Since the quantity of fuel gas injected can be increased by the combustion catalyst, the fuel reformer can be made compact. Since the combustion catalyst has high oxidation property, combustion reaction can be started from a low temperature, and starting time can be shortened. The energy required for heating is suppressed by the shortened starting time. Since the usage amount of expensive rhodium is reduced, the fuel reformer is economical. Since carrier (I) has higher heat conductivity than carrier (II), the rate of heat transfer to the catalyst is increased and arrival time of modification-start temperature by heat tracing is shortened. The modification catalyst has excellent heat resistance. Since a noble metal is used as active type, active deterioration is suppressed.    DETAILED DESCRIPTION - A fuel reformer consists of a modification portion which modifies a fuel by catalytic reaction to produce hydrogen, a fuel supplier for supplying fuel to the modification portion, and an air supplier for supplying air to the modification portion. The modification portion is provided with catalytic converter (11A) containing a combustion catalyst supported by support (I), and catalytic converter (11B) containing a modification catalyst supported by support (II) and provided at the downstream of catalytic converter (11A). The fuel reformer is driven in a high-pressure state than atmospheric pressure.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of the fuel reformer. (Drawing includes non-English language text)    Fuel reformer (10)    Modification portion (11)    Catalytic converters (11A,11B)    Fuel supplier (12)    Air supplier (13)