The present invention relates to polymer membranes for separating olefins from paraffins which have the similar molecular size and close boiling point. More particularly, it relates to a silver salt-containing facilitated transport membrane for olefin separation, and also a method for producing the same. An object of the present invention is to provide a silver salt-containing facilitated transport membrane for olefin separation having improved stability, and also a method for preparing the same, which exhibits no deterioration in membrane performance even when operated for an extended period of time. The facilitated transport membrane for olefin/paraffin separation of the present invention comprises a polymer, a silver salt, and a phthalate compound represented by the following formula (1) wherein R denotes an alkyl group of 2 to 8 carbon atoms or a phenyl group.