PURPOSE: To obtain the title composition which is excellent in adhesiveness to various substrates and anticorrosiveness, is scarcely attacked by warm water 6r chemicals such as an acid and an alkali, has excellent film-forming properties at low temperature and maintains such an excellent performance that it does not form a mottled pattern due to poor film-forming properties when baked.

CONSTITUTION: The title composition comprises an aqueous dispersion of a modified epoxy resin obtained by reacting an aromatic epoxy resin (A) with a modified polyester resin (B) made by copolymerizing a polyester resin, such as an acrylic-modified alkyd resin or an acrylic-modified epoxy ester resin, having a reactive double bond in the molecule with a carboxylated vinyl monomer at a specified ratio of component A to component B.