Provided are a functional polymer membrane including: a surface layer; and an anion exchange membrane or a cation exchange membrane, in which the surface layer contains a polymer which includes a cross-linked structure having, in a cross-linking unit, an ionic group with a charge opposite to a charge of an ionic group included in at least one of the anion exchange membrane or the cation exchange membrane; a production method thereof, and a stack or a device provided with a polymer functional membrane.