A liner for a high pressure gas container includes a resin composition containing a polyphenylene sulfide resin and an olefin based resin. The resin composition has a methane gas permeability coefficient of 1.7.times.10.sup.-16 molm/m.sup.2sPa or smaller at 40.degree. C., and tensile elongation of 50% or greater after fracture at 23.degree. C. A high pressure gas container having such a liner is also provided.