NOVELTY - An anion exchange membrane comprises a resin phase containing 20-96 mass% of a polymer having repeating units and 4-80 mass% of a thermoplastic polymer having no ion exchange groups.    USE - The anion exchange membrane is used for an electrodialytic process for the concentration of sea water, demineralization of brine water, concentration or recovery of an acid or recovery of valuable metals, and for a diffusion catalytic process for e.g., recovery of an acid. It is also used for a separator of a fuel cell or a secondary battery. It is also in the solution treating apparatus (claimed) for concentrating, demineralizing and purifying hydroxide from a solution having a pH of at least10 by electrodialysis or diffusion dialysis, for the solution-treating apparatus which requires high temperature sterilization or for a self generating type demineralizing water production apparatus.    ADVANTAGE - The anion exchange membrane is excellent in the alkali resistance and the heat resistance, and has a high mechanical strength. It is useful for an application in which a conventional anion exchange membrane has a problem in the durability.    DETAILED DESCRIPTION - An anion exchange membrane comprises a resin phase containing 20-96 mass% of a polymer having repeating units represented by the following formula (1) and 4-80 mass% of a thermoplastic polymer having no ion exchange groups.    A = 3-8C alkylene or 4-9C alkyleneoxyalkyl;    R1, R2, R3 = H, 1-6C alkyl or a hydroxyalkyl;    X = anion    Any hydrogen atom bonded to the benzene ring may be substituted by an alkyl group or a halogen atom. INDEPENDENT CLAIMS are also included for:    (A) a process of producing the anion exchange membrane, comprising mixing the thermoplastic polymer having no ion exchange groups with a polymerizable component containing a monomer of formula (2), and then polymerizing the polymerizable component; and    (B) a solution treating apparatus, comprising an electrodialytic or diffusion dialytic mechanism employing the anion exchange membrane.    A = as above;    Z = Cl, Br, I, hydroxyl group, tosyl group, primary or tertiary amine, or -NR1R2R3 group;    R1, R2, R3 = H, 1-6C alkyl or hydroxyl.