PURPOSE: To obtain a stable nonaqueous polymer dispersion comprising dispersed particles of a small diameter, by adding an orthocarboxylic acid ester to a nonaqueous polymer dispersion obtained by subjecting an ethylene monomer to a specified treatment and removing a trace amount of water from the mixture.

CONSTITUTION: A mixture of a monofunctional ethylenic monomer with 0.5W80wt.% polyfunctional ethylenic monomer is emulsion-polymerized in the presence of an organic sulfonic acid or organic sulfate salt surfactant to obtain an aqueous polymer dispersion. After the addition of an alcohol solvent or a ketone solvent to this dispersion, an acid compound is added to the mixture, and the temperature of the system is kept at 60W90°C. While the mixture is being kept in a suspended state, the surfactant is completely converted into an organic sulfonic acid compound or an organic sulfuric acid compound, and the suspension is separated into two layers to remove at least 95wt.% water contained in the suspension. A trace amount of remaining water is removed from the nonaqueous polymer dispersion (B) left after removing the separated water in said step (A) by, for example, adding an orthocarboxylic acid ester to it and heating the mixture to obtain the purpose nonaqueous dispersion.