PURPOSE: To obtain the titled resin, having excellent drying properties, transpar ency, ultraviolet ray resistance, compatibility, etc., and useful as coatings, etc., by reacting a specific alkyd polymer with cellulose acetate butyrate under specific conditions.

CONSTITUTION: (A) An alkyd resin obtained by blending and reacting (i) an acid component consisting essentially of (i) a 4W10C polybasic acid or a reactive acid derivative thereof in one molecule with (ii) an alcohol component consisting essentially of a polyhydric alcohol having 2W6 hydroxyl groups in one molecule so as to provide 1.1/1.0W1.6/1.0 (equivalent ratio) of hydroxyl groups/carboxyl groups and having JWZ viscosity measured by using a 60wt.% solution thereof in xylene and ≤15 acid value is reacted with (B) 5W80wt.% cellulose acetate butyrate in (C) an aromatic hydrocarbon solvent to afford the aimed resin.