To provide an aqueous emulsion of a hydroxy group-containing aqueous (meth)acrylic composite urethane resin composition which is a hydroxy group-containing aqueous emulsion without substantially containing an organic solvent and exhibits antistaining properties, especially excellent water resistance.

The aqueous resin emulsion of the resin composition is produced as follows. A diisocyanate is reacted with a polyol and an ionic group-forming compound in an acrylic monomer without containing an active hydrogen group to provide an acrylic monomer solution of a urethane prepolymer. The resultant solution is passed through a neutralizing step and an emulsifying step and then mixed with a hydroxy group-containing acrylic monomer. Chain extension and polymerization of the acrylic monomer are subsequently carried out. A surface coating agent comprises an aqueous curing resin composition consisting essentially of the aqueous emulsion of the resin composition and a water-dispersible polyisocyanate.