TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The component (1) contains manganese-lanthanum oxide having perovskite type structure obtained by X-ray diffraction measurement. The perovskite type oxide further contains metallic element chosen from alkali metal, alkaline earth metal and lanthanoid series rare-earth metal. Alternately, the catalyst component (1) is noble metal catalyst containing platinum, palladium, rhodium, iridium or ruthenium and further containing alkali metal and/or alkaline earth metals. The catalyst component (2) is metal and/or metal oxide catalyst containing element chosen from groups 6-10, preferably aluminum oxide, titanium oxide, zirconium oxide, cerium oxide, lanthanum trioxide, zeolite, magnesium oxide, calcium oxide, barium oxide, yttrium oxide, tungsten oxide or silicon dioxide, and further contains silica-alumina and titanium type complex oxide and alkali metal and/or alkaline earth metal. The hydrogen production catalyst contains cobalt, iron, nickel or molybdenum and further contains alkali metal, alkaline earth metal or rare earth element, and metal oxide chosen from alumina, silica, zirconia, titania, ceria, lanthanum trioxide, magnesium oxide, calcium oxide, barium oxide, and strontium oxide. Preferred Process: The addition amount of oxygen with respect to 1 mol of ammonia is 0.05-0.75 mol. The catalyst component (1) is arranged in the front stage and the catalyst component (2) is arranged in the back stage with respect to the flow of the gas containing ammonia and oxygen. The ammonia in the gas is burnt by the catalyst component (1), in presence of oxygen and combustion heat is generated. The gas heated with the combustion heat is contacted with the ammonia decomposition catalyst arranged in the back stage. The usage amount of the catalyst component (1) with respect to 100 volume parts of the catalyst component (2) is 5-100 volume parts. The reactive gas supply temperature to the catalyst component (2) is 300-1100 degrees C. The reactive gas is supplied to the ammonia combustion catalyst at space velocity of 10000-1000000 hour-1 and heated at 100-500 degrees C.