A water-soluble acrylic resin which is prepared by neutralizing with a neutralizing agent an acrylic copolymer formed by copolymerizing (a) an alkylene oxide group-containing (meth)acrylate, (b) a cyclic saturated hydrocarbon group-containing (meth)acrylate, (c) a hydroxyl group-containing unsaturated monomer other than the monomer (a), and (d) other unsaturated monomer; a resin composition used for a water-based coating composition and containing, as a vehicle component, the above water-soluble acrylic resin; a water-based coating composition containing, as major components, (A) at Least one resin selected from the group consisting of a water-soluble resin and a water-dispersible resin and (B) a pigment, said pigment (B) being subjected to dispersion treatment; with a water-soluble acrylic resin (C), which is prepared by neutralizing with a neutralizing agent an acrylic copolymer formed by copolymerizing (a) an alkylene oxide group-containing (meth)acrylate, (b) a cyclic saturated hydrocarbon group-containing (meth)acrylate, and (e) other unsaturated monomer, followed by being mixed with the resin (A) to form a water-based coating composition; a coating method comprising coating a base coat coating composition onto a substrate followed by coating a top clear coating composition, the above water-based coating composition being used as the base coat coating composition.