The hydroxyl-containing resin (A) used in the water-based paint of the present invention includes resins having at least one hydroxyl group per molecule, specific examples including such resins as acrylic resin, polyester resin, polyether resin, polycarbonate resin, polyurethane resin, epoxy resin, alkyd resin and the like, which contain hydroxyl group and also acid group such as carboxyl group, w