TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Apparatus: The apparatus further comprises:(1) a recovering gas supply unit for supplying an inert gas or water vapor to the reforming unit, where the activity of the reforming catalyst is recovered by heating the catalyst while supplying the inert gas or water vapor to the reforming unit;(2) a thermometer for detecting a temperature of the reforming catalyst, where the activity of the reforming catalyst is recovered by heating the reforming catalyst while supplying the inert gas or water vapor to the reforming unit, after stopping supplying the raw material to the reforming unit when a temperature of the reforming catalyst becomes a predetermined temperature;(3) a sensor for detecting a concentration of hydrogen gas, wherein activity of the reforming catalyst is recovered when a concentration of hydrogen gas becomes not higher than a predetermined concentration; and(4) a desulfurizer for removing a sulfide from the raw material. EXAMPLE - Using a fuel reforming apparatus a hydrogen rich reformed gas was generated by heating a reforming unit with the heating unit while supplying the raw material of city gas and water to the reforming unit and steam-reforming the raw material. First, the steam-reforming was conducted by using, as the hydrocarbon type fuel, city gas not being subjected to desulfurating or diluting treatment at all. The conversion rate declined gradually with time after the starting of the steam reforming whereas the temperature of the reforming catalyst rose gradually. The conversion rate, which was at 99 % at the starting of the reforming declined to around 90 % at 30 hours after starting the reforming. On the other hand, the temperature of the reforming catalyst rose 150 degreesC from the temperature detected just after the starting of steam reforming. At this point, the temperature of the reforming catalyst had reached the predetermined maximum temperature, therefore the supply of raw material to the reforming unit from the raw material supply unit was stopped. Then an operation for recovering the reforming catalyst was conducted by heating the reforming unit with the heating unit while supplying an inert gas to the reforming unit from the inert gas supply unit. After recovering the activity for the predetermined duration of time, another steam reforming was conducted. The conversion rate rose to not less than 99 %, which is almost as high as the initial performance. On the other hand, the temperature of the reforming catalyst declined to the temperature detected just after the starting of the steam reforming. Consequently, it was confirmed that the activity of the reforming catalyst was recovered. Further, the same operation as above was repeated for 10 times or more and subsequently the conversion rate was tested. Then, it was confirmed that the activity was recovered in the same way as at the first time.