PURPOSE: To highly refine an inert gas by first allowing a getter material to come into contact with an inert gas to capture oxygen under heating, then allowing the inert gas to come into contact with an adsorbent, and further, allowing the inert gas diluted with hydrogen to come into contact with the getter material under heating to generate water, and finally using the water for regeneration.

CONSTITUTION: Reaction cylinders A, B are filled with a getter material 3 mainly composed of Ni or Cu, then an inert gas is introduced from an inlet 1 and is allowed to come into contact with the getter material under heating by a heater 4. Consequently, oxygen in the inert gas is captured by the getter material 3. Next, a refined gas removes residual moisture and other trace impurities in the absorption cylinders C, D filled with an absorbent 19 at normal temperature. In this case, during the refining step of the reaction cylinder A and the adsorption cylinder C, the reaction cylinder B and the adsorption cylinder D are in a regeneration step. If the getter material 3 is allowed to come into contact with the inert gas diluted with hydrogen under heating, the captured oxygen reacts chemically with hydrogen to give water. This water is recycled to the regeneration step of the getter matrial and the regeneration step of the adsorbent 19 in the adsorptioon cylinder D.