To obtain an aqueous coating composition improved in adhesion to a brittle surface by combining an emulsion polymer having specified glass transition temperature and average particle size with a specified amount of a water- soluble alkoxylated amine.

This composition contains an emulsion polymer and a water-soluble alkoxylated amine in an amount of 0.25-10 wt.% of the polymer. The polymer has a glass transition temperature of -20°C to 100°C and an average particle size lower than 120 nm and is formed by the copolymerization of at least one ethylenically unsaturated nonionic monomer having a water solubility lower than 8% and at least one acid monomer in such an amount as to give the polymer an acid value of 30-100. Methyl (meth)acrylate, butyl (meth)acrylate, styrene, butadiene, etc., are listed as the ethylenically unsaturated nonionic monomer.