Studies on ion exchange membranes with permselectivity for specific ions in electrodialysis are reviewed. Studies have been made with respect to : (1) control of permselectivity of ions with the same charge on the basis of ionic size difference, (2) separation of ions with the same charge by oppositely charged ion exchange groups on the membrane surface, and (3) control of permselectivity of ions with the same charge by specific interaction of ion exchange groups of the membrane with specific ions. Several methods are used in industrial electrodialysis to separate monovalent ions from divalent ions. However, separation of ions with the same charge and the same valence has not been achieved. It is necessary to find out new concepts for this purpose.