A functional polymer membrane comprising a polymer containing at least a structure represented by the following Formula: wherein: R 1 and R 2 each independently represent a hydrogen atom or a linear or branched C 1 -C 10 alkyl group; R 3, R 4, R 5 and R 6 each independently represent a substituent selected from a C 1 -C 30 alkyl group, a C 3 -C 30 cycloalkyl group, a C 2 -C 30 alkenyl group, a C 2 -C 30 alkynyl group, a C 6 -C 30 aryl group, a C 0 -C 30 amino group, a C 1 -C 30 alkoxy group, a C 6 -C 30 aryloxy group, a C 2 -C 30 heterocyclic oxy group, a C 1 -C 30 acyl group, a C 2 -C 30 alkoxycarbonyl group, a C 7 -C 30 aryloxycarbonyl group, a C 2 -C 30 acyloxy group, a C 2 -C 30 acylamino group, a C 2 -C 30 alkoxycarbonylamino group, a C 7 -C 30 aryloxycarbonylamino group, a C 1 -C 30 alkyl- or arylsulfonylamino group, a C 0 -C 30 sulfamoyl group, a C 1 -C 30 carbamoyl group, a C 1 -C 30 alkylthio group, a C 6 -C 30 arylthio group, a C 2 -C 30 heterocyclic thio group, a C 1 -C 30 alkyl- or arylsulfonyl group, a C 1 -C 30 alkyl- or arylsulfinyl group, a C 1 -C 30 ureido group, a C 1 -C 30 phosphoric acid amide group, a hydroxyl group, a mercapto group, a halogen atom, a cyano group, a sulfo group, a carboxyl group, an oxo group, a nitro group, a hydroxamic group, a sulfino group, a hydrazino group, an imino group, a C 1 -C 30 heterocyclic group, a C 3 -C 40 silyl group and a C 3 -C 40 silyloxy group; k1, k2, k3 and k4 each independently represent 0 or an integer; in the case where a plurality of R 3, R 4, R 5 and R 6 are present, the plural R 3, R 4, R 5 and R 6 may be respectively identical to or different from each other, or may be bonded to each other and form a saturated or unsaturated ring fused to the phenyl ring; A 1, A 2, A 3 and A 4 each independently represent a single bond or a divalent linking group; M 1 represents a hydrogen ion, an organic base ion or a metal ion; in the case where a plurality of M 1 are present, the plural M 1 may be identical to or different from each other; n1 and n2 each independently represent an integer from 1 to 4; m1 and m2 each independently represent 0 or 1; J 1 represents a single bond, -O-, -S-, -SO 2 -, -CO-, -CR 8 R 9 - or an alkenylene group; R 8 and R 9 each independently represent a hydrogen atom, a methyl group or a fluorine atom; p represents an integer of 1 or larger; and q represents an integer from 0 to 4. R 1 and R 2 each independently represent a hydrogen atom or a linear or branched C 1 -C 10 alkyl group; R 3, R 4, R 5 and R 6 each independently represent a substituent selected from a C 1 -C 30 alkyl group, a C 3 -C 30 cycloalkyl group, a C 2 -C 30 alkenyl group, a C 2 -C 30 alkynyl group, a C 6 -C 30 aryl group, a C 0 -C 30 amino group, a C 1 -C 30 alkoxy group, a C 6 -C 30 aryloxy group, a C 2 -C 30 heterocyclic oxy group, a C 1 -C 30 acyl group, a C 2 -C 30 alkoxycarbonyl group, a C 7 -C 30 aryloxycarbonyl group, a C 2 -C 30 acyloxy group, a C 2 -C 30 acylamino group, a C 2 -C 30 alkoxycarbonylamino group, a C 7 -C 30 aryloxycarbonylamino group, a C 1 -C 30 alkyl- or arylsulfonylamino group, a C 0 -C 30 sulfamoyl group, a C 1 -C 30 carbamoyl group, a C 1 -C 30 alkylthio group, a C 6 -C 30 arylthio group, a C 2 -C 30 heterocyclic thio group, a C 1 -C 30 alkyl- or arylsulfonyl group, a C 1 -C 30 alkyl- or arylsulfinyl group, a C 1 -C 30 ureido group, a C 1 -C 30 phosphoric acid amide group, a hydroxyl group, a mercapto group, a halogen atom, a cyano group, a sulfo group, a carboxyl group, an oxo group, a nitro group, a hydroxamic group, a sulfino group, a hydrazino group, an imino group, a C 1 -C 30 heterocyclic group, a C 3 -C 40 silyl group and a C 3 -C 40 silyloxy group; k1, k2, k3 and k4 each independently represent 0 or an integer; in the case where a plurality of R 3, R 4, R 5 and R 6 are present, the plural R 3, R 4, R 5 and R 6 may be respectively identical to or different from each other, or may be bonded to each other and form a saturated or unsaturated ring fused to the phenyl ring; A 1, A 2, A 3 and A 4 each independently represent a single bond or a divalent linking group; M 1 represents a hydrogen ion, an organic base ion or a metal ion; in the case where a plurality of M 1 are present, the plural M 1 may be identical to or different from each other; n1 and n2 each independently represent an integer from 1 to 4; m1 and m2 each independently represent 0 or 1; J 1 represents a single bond, -O-, -S-, -SO 2 -, -CO-, -CR 8 R 9 - or an alkenylene group; R 8 and R 9 each independently represent a hydrogen atom, a methyl group or a fluorine atom; p represents an integer of 1 or larger; and q represents an integer from 0 to 4.