PURPOSE: To obtain an aqueous resin composition useful for coating metal cans for processed foods, providing a coating film having excellent hardness, steam resistance, water resistance, luster, etc., comprising a specific aqueous polymer and an amino resin.

CONSTITUTION: This resin composition comprises an aqueous polymer prepared by neutralizing a carboxyl group of a copolymer, consisting of (A) 3-30wt.% of a macromonomer containing a radically polymerizable group at one end of a (meth)acrylonitrile/styrene copolymer, (B) 3-20wt.% of an α,β-ethylenic unsaturated carboxylic acid, (C) 5-40wt.% of a hydroxyalkyl (meth)acrylic acid hydroxyalkyl and (D) 10-89wt.% of a vinyl monomer based on 100wt.% of the components A+B+C+D, with a base such as an organic amine or ammonium and (E) an amino resin such as an alkyl etherified melamine resin or an alkyl etherified benzogunamine resin.