To provide an ion exchange polymer which has a practical ion conductance as a barrier membrane material used for electric cells (especially, for a polymer electrolyte fuel cell) and which has a sufficient heat resistance to heat generated by use of the electric cell.

The ion exchange polymer includes a plurality of heterocyclic groups each of which is a monovalent cation including a nitrogen atom. Since such ion exchange polymer has excellent heat resistance in comparison with anion exchange polymers mainly used conventionally, the ion exchange polymer can be suitably used especially as a barrier membrane used for polymer electrolyte fuel cells.