A method for forming a bright coating film includes: (1) applying a water-based primer coating material composition to a substrate to form a water-based primer coating film; (2) applying a water-based bright coating material (i) to the water-based primer coating film to form a first base coating film; (3) applying a water-based bright coating material (ii) to the first base coating film to form a second base coating film; (4) applying a high-solid clear coating material to the second base coating film to form a clear coating film; and (5) heat-curing the water-based primer coating film, the first base coating film, the second base coating film, and the clear coating film simultaneously to form a cured coating film, wherein the water-based primer coating material composition includes a water-based non-chlorinated polyolefin resin (A), a water-based polyurethane resin (B), a water-based epoxy resin (C), and an internally crosslinked acrylic particle emulsion (D), and an emulsifier.