Water-based coating composition, and multi-layer coating film

A method for producing a water-based coating composition, comprising

• a step of mixing and dispersing a coloring pigment (D) and a comb-structured non-ionic pigment dispersing agent in an aqueous medium using a dispersion medium to produce a coloring pigment dispersion (ii), wherein
• an amount of the comb-structured non-ionic pigment dispersing agent is 65 to 150 parts by mass as solid content mass parts based on 100 parts by mass of the coloring pigment (D),
• the dispersion medium has a particle diameter of 0.03 mm to 0.05 mm, and
• a material of the dispersion medium is zirconia;
• and
• a step of mixing a coating film-forming resin (i) and the coloring pigment dispersion (ii) to produce the water-based coating composition, wherein
• the coating film-forming resin (i) comprises
• an acrylic resin emulsion (A) having an average particle diameter of 100 nm or less in an amount of 10 to 60% by mass in terms of a resin solid content of the coating film-forming resin (i),
• a water-soluble acrylic resin (B) in an amount of 5 to 40% by mass in terms of the resin solid content of the coating film-forming resin (i), and
• a melamine resin (C) in an amount of 20 to 40% by mass in terms of the resin solid content of the coating film-forming resin (i).