PURPOSE: To obtain a water-based coating composition capable of forming coating films excellent in water resistance, processing resistance and coatability, containing, as the resin components, an amidated polyester resin and a water- based amino resin at specified proportions.

CONSTITUTION: This composition contains, as the resin components, (A) a polyester having acid and/or acid anhydride (e.g. oil-free polyester resin, graft-modified polyester resin), (B) 2-80wt.% of an amidated polyester resin to which at least one kind of amine selected from ammonia, primary amines and secondary amines has been partially or wholly added, and (C) 10-60wt.% of a water-based amino resin (e.g. methylol-modified melamine resin, benzoguanamine resin, spiroguanamine resin).