NOVELTY - Argon gas containing oxygen, hydrogen, carbon monoxide, and nitrogen as an impurity is contacted with a metal oxide catalyst, hydrogen and carbon monoxide in gas are reacted with the metal oxide catalyst, and water, carbon dioxide, and metal are produced. The produced metal is reacted with oxygen, and metal oxide catalyst is regenerated. The produced carbon dioxide and water are made to adsorb to an adsorption agent by a pressure-swing-adsorption method with nitrogen. Nitrogen which is not adsorbed is adsorbed to adsorption agent by temperature swing adsorption method.    USE - Purification of argon gas used as furnace atmosphere gas used for silicon monocrystal pulling furnace, ceramic sintering furnace, vacuum degassing installation for steel manufacture, silicon plasma melting apparatus for solar cells, and polycrystalline-silicon casting furnace.    ADVANTAGE - The argon gas is economically and effectively purified at high purity.    DETAILED DESCRIPTION - Argon gas containing oxygen, hydrogen, carbon monoxide, and nitrogen as an impurity is contacted with a metal oxide catalyst, hydrogen and carbon monoxide in gas are reacted with the metal oxide catalyst, and water, carbon dioxide, and metal are produced. The produced metal is reacted with oxygen, and metal oxide catalyst is regenerated. The produced carbon dioxide and water are made to adsorb to an adsorption agent by a pressure-swing-adsorption method with nitrogen. Nitrogen which is not adsorbed after appropriate time by pressure-swing adsorption method is adsorbed to adsorption agent by temperature swing adsorption method at -10 degrees C to -50 degrees C. An INDEPENDENT CLAIM is included for purifier ( alpha ) of argon gas, which has a reactor (3) with which the argon gas is introduced, and an adsorption apparatus (5) having pressure swing adsorption unit (10) and temperature swing adsorption unit (20). The pressure swing adsorption unit is connected to the reactor such that adsorption agent is adsorbed by a pressure-swing adsorption method. The temperature swing adsorption unit is connected to the pressure swing adsorption unit such that adsorption agent is adsorbed by the thermal swing adsorption method.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of purifier of argon gas.    Reactor (3)    Adsorption apparatus (5)    Pressure swing adsorption unit (10)    Temperature swing adsorption unit (20)    Purifier (Alpha)