Disclosed herein is an ion conductive polymer comprising a unit represented by Formula (1) below: —SO2[N−SO2(M+)]X1-  (1) wherein X1 is an integer greater than 1, and M+ is H+ or Li+. Further disclosed is an imide monomer represented by Formula (A) below: Z1-SO2[N−SO2M+]Y-Z2   (A) wherein Y is an integer of 2 or greater, Z1 is OH, F, Cl, Br, I or NZ3Z4 (in which Z3 and Z4 are each independently H, M or SiMe3, and M is a metal element), Z2 is OH, F, Cl, Br, I or NZ3Z4 (in which Z3 and Z4 are each independently H, M or SiMe3, and M is a metal element), and M+ is H+ or Li+.