NOVELTY - Mixed gas containing hydrogen obtained by water vapor modification of hydrocarbon group raw material is introduced to adsorption towers (A-C) filled with specific adsorption agent, and unwanted gas in mixed gas is adsorbed to adsorption agent. Product gas with high hydrogen gas concentration is discharged from the tower. The unwanted gas is desorbed from the adsorption agent, and desorbed gas containing gas remaining in the tower and unwanted gas are discharged from the tower. Adsorption and desorption are repeatedly carried out, and separation of hydrogen is enabled.    USE - Separation of hydrogen gas from mixed gas containing hydrogen, used as industrial gas for glass melting, semiconductor manufacture, optical fiber manufacture, cutting and hardening of oil, and used as fuel for fuel cell electric vehicle.    ADVANTAGE - The hydrogen gas is efficiently separated from the mixed gas.    DETAILED DESCRIPTION - Mixed gas containing hydrogen obtained by water vapor modification of hydrocarbon group raw material is introduced to adsorption towers (A-C) filled with adsorption agent, and unwanted gas contained in mixed gas is adsorbed to adsorption agent by pressure-fluctuation adsorption type gas separation method. Product gas with high hydrogen gas concentration is discharged from the adsorption tower. The unwanted gas is desorbed from the adsorption agent, and desorbed gas containing gas remaining in the tower and unwanted gas are discharged from the tower. Adsorption and desorption process are repeatedly carried out, and separation of hydrogen is enabled. The adsorption agent contains activated carbon group adsorption agent (D) having filling rate of 60-80% and provided in upstream of flow direction of mixed gas in the tower, and zeolite group adsorption agent (E) having filling rate of 40-20% and provided in downstream of flow direction of mixed gas in the tower. An INDEPENDENT CLAIM is included for apparatus for separating hydrogen gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of pressure-fluctuation adsorption type gas separation apparatus. (Drawing includes non-English language text)    Valve (7,8)    Adsorption towers (A-C)    Activated carbon group adsorption agent (D)    Zeolite group adsorption agent (E)    Separation apparatus (X)