Abstract: There is disclosed a method for removing nitrogen oxides of exhaust gas using natural manganese ores. In the method, ammonia is used as a reductant to selectively reduce the nitrogen oxides in the presence of a catalyst prepared from the natural manganese ores. The catalyst allows nitrogen oxides to be completely removed from exhaust gas at a relatively low temperature of 130-250° C. without discharging unreacted ammonia through oxidation reaction. The catalyst is superior in economic terms in addition to preventing the deleterious effects which occur when discharging ammonia.