A water-based coating composition which is prepared by dispersing a thermosetting coating composition in water in the presence of a suspension stabilizer consisting of a block copolymer and, if necessary, ridding the obtained aqueous dispersion of organic solvents and has a mean particle diameter of 0.1 to 10 mu m, characterized in that the block copolymer is a product of neutralization with a basic substance of a compound (c) obtained by radical-polymerizing a compound (a) of the general formula (1) with a polymerizable unsaturated monomer (b) in the presence of a radical polymerization initiator.
