Provided is an ion exchange membrane including an ionic vinyl alcohol polymer having a cation exchange group or an anion exchange group. The ion exchange membrane 1 includes a porous support 3 and the ionic vinyl alcohol polymer. The porous support is provided, in a thickness direction from one surface thereof, with an impregnated layer 2 at least a part of which is impregnated with the ionic vinyl alcohol polymer. The ionic vinyl alcohol polymer includes an ionic vinyl alcohol polymer having an ion exchange group selected from a cation exchange group or an anion exchange group. The ion exchange membrane has a zeta potential value (ζ1) at one surface and a zeta potential value (ζ2) at the other surface, which are represented by the formula (1). (|ζ1|)−|ζ2|)/|ζ1|