To provide a water-based coating composition capable of forming cured coating films having excellent coating film appearances such as excellent leveling properties, gloss and water resistance, and having high hardness.

This water-based coating composition comprises the aqueous dispersion of (A) an emulsifying polymer having a number-average mol. wt. of >50,000 and obtained by the emulsion polymerization of (a-2) an unsaturated monomer in the presence of the aqueous dispersion of (a-1) a self-emulsion type acrylic resin having a number-average mol. wt. of 1,000 to 100,000 and a hydroxy group value of 20 to 150, and (B) a water-dispersible polyisocyanate.