or carbonylic acid examples of this polymer include polyvinylpyrrolidone pvp poly 2 ethyl 2 oxazoline polyvinylmethylketone polyvinylformal polyvinylacetate cellulose acetate ca cellulose acetate butyrate cab polyacrylate polymethylmethacrylate pmma polyacrylic acid and the like in the polymer membranes according to the present invention the molar ratio of silver salt monomer unit of polymer ranges from 0 5 3 and preferably 1 2 examples of the silver salt which can be used in the practice of the present invention include agbf 4 agpf 6 agso 3 cf 3 agclo 4 agsbf 6 and the like in addition other silver salts which can chemically bind to the functional group of the polymer may also be used the phthalate compound is contained at the amount of 0 05 to 10 by weight and preferably 1 to 5 by weight relative to the weight of the polymer if the phthalate compound content is below 0 05 by weight it is disadvantageous in that an improvement of performance and stability of the separation membrane is insufficient on the other hand if the phthalate content exceeds 10 by weight it is also disadvantageous in that the permeance of olefins is significantly reduced furthermore the facilitated transport membrane for olefin paraffin separation is produced by a method which comprises the steps of successively dissolving a.