PURPOSE: To make it possible to improve the mechanical strength and durability of an anion exchange membrane by preventing its core material from being degraded by dehydrochlorination or the like without detriment to the high performance inherent in the membrane, by combining a base material comprising a vinyl chloride or vinylidene chloride polymer with a specified monomer.

CONSTITUTION: An anion exchange membrane wherein the base material comprises a vinyl chloride or vinylidene chloride polymer and the monomer unit having a functional group suitable for introducing an exchange group is formed of a 4-vinylpyridine unit and a vinylphenethylamine unit. The vinylphenethylamine unit is represented by the formula (wherein R1 and R2 are each methyl or ethyl and both of R1 and R2 are preferably methyl groups). The molar ratio of 4-vinylpyridine (a) to vinylphenethyl (b) is preferably such that b/(a+b)=0.1W0.9 by molar ratio.