NOVELTY - Methane is purified using a methane purifier having adsorption towers (1,2), communicating path (L2), supply path (L1), steam extraction paths (L4,L5) and exhaustion path (L3). Original gas containing methane is supplied from supply path. Non-absorbed gas which is not adsorbed in tower (1) is supplied to tower (2) through path (L2). The gas adsorbed in adsorption agent of tower (1) is supplied through path (L4). Waste gas which is not adsorbed in tower (2) is supplied through exhaustion path. The gas adsorbed in adsorption agent of tower (2) is supplied through path (L5).    USE - Purification of methane.    ADVANTAGE - Methane gas is obtained with high purity.    DETAILED DESCRIPTION - Methane is adsorbed from original gas containing methane as main component into methane absorption agent and impurity which is not adsorbed, is separated, using a methane purifier. The methane purifier has a methane adsorption portion having an adsorption tower (1) filled with a methane adsorption agent, adsorption tower (2) having small capacity than tower (1), a communicating path (L2) for connecting towers in series, a supply path (L1) for supplying original gas to tower (1), a steam extraction path (L4) for discharging gas passed through adsorption agent in the tower (1), a steam extraction path (L5) for discharging gas passed through adsorption agent in the tower (2) and an exhaustion path (L3) from tower (2). Original gas containing methane is supplied from supply path until pressure of tower (1) is set to primary pressure in closed state of communicating path. The supply of gas is stopped. Non-absorbed gas which is not adsorbed in tower (1) is supplied to tower (2) through communicating path until pressure in tower (2) is set to secondary pressure differing from primary pressure. The gas adsorbed in adsorption agent of tower (1) is supplied through path (L4) under recovery pressure. The supply of non-absorption gas from tower (1) is stopped. Waste gas which is not adsorbed in tower (2) is supplied through exhaustion path until pressure in tower (2) is set to tertiary pressure higher than recovery pressure. The gas adsorbed in adsorption agent of tower (2) is supplied through path (L5) under recovery pressure. Thus, methane is purified.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of methane purifier. (Drawing includes non-English language text)    Adsorption towers (1,2)    Supply path (L1)    Communicating path (L2)    Exhaustion path (L3)    Steam extraction paths (L4,L5)