NOVELTY - Separation of methane and nitrogen involves carrying out pressurization process after supplying source gas and increasing pressure in an adsorption tower, adsorbing methane with adsorption agent (21, 22) for gas separations filled in the adsorption tower, and taking out nitrogen, carrying out pressure equalization process which moves gas in adsorption tower where the pressure is increased to another adsorption tower, in which the pressure in the adsorption tower is lowered.    USE - Separation of nitrogen and methane used as fuel for electric power generation.    ADVANTAGE - The method enables economical separation of methane and nitrogen having high purity, with high recovery rate.    DETAILED DESCRIPTION - Separation of methane and nitrogen from a source gas which is mixed gas containing methane and nitrogen with the pressure-fluctuation-type adsorption method using the adsorption tower of two or more columns, involves carrying out pressurization process after supplying the source gas and increasing the pressure in an adsorption tower, adsorbing methane with adsorption agent for gas separations filled in the adsorption tower, and taking out nitrogen, carrying out pressure equalization process which moves the gas in the adsorption tower where the pressure is increased to another adsorption tower, in which the pressure in the adsorption tower is lowered and it has the regeneration process which desorbs the methane adsorbed in the adsorption agent. The pressurization process, adsorption process, pressure equalization process, and regeneration process are performed in each of the two or more columns of adsorption tower. In the pressure equalization process, the gas in the adsorption tower after the completion of an adsorption process moves to another adsorption tower after the completion of the regeneration process. The concentration of methane recovered in the regeneration process is 70% or more and the recovery rate is 95% or more. The concentration of nitrogen recovered in the adsorption process is 95% or more. The amount of equilibrium adsorptions of the adsorption agent by methane is more than nitrogen. An INDEPENDENT CLAIM is included for adsorption agent.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of apparatus for separation of methane and nitrogen.    Separation apparatus (1)    Massflow controllers (4,5)    Pressure gauge (6-9)    Blower (10)    Adsorption agents (21, 22)