PROBLEM TO BE SOLVED: To provide a method capable of stably and efficiently performing the carbon dioxide modification of hydrocarbon at a low cost without causing the problem, e.g., that catalyst activity is deteriorated by carbon precipitation onto a catalyst.SOLUTION: High temperature sintered ores exhausted from a sintering machine are charged to a reaction container A for carbon dioxide modification, the carbon dioxide modification of hydrocarbon is used with the sintered ores as a catalyst and a heat source, and further, the sintered ores in the reaction container A are exchanged with new sintered ores per prescribed time. Since the high temperature sintered ores can be continuously fed from the sintering machine, by exchanging the sintered ores utilized as a catalyst and a heat source with new sintered ores per prescribed time, even if carbon is precipitated on the catalyst, it does not reach a state where catalyst activity is deteriorated, and further, the function as a heat source can be stably maint
