Abstract: This invention provides a paint film forming method comprising applying color base paint onto rigid resin parts and then clear paint and curing the two paint films, which is characterized by using, as said clear paint, a clear paint comprising 60-90% by weight of a hydroxyl-containing acrylic resin (A) and 10-40% by weight of a curing agent (B), based on the combined solid content of the acrylic resin (A) and the curing agent (B),

Abstract: A process to form a multilayer coating film, which is excellent in smoothness and capable of preventing a generation of popping even in case of a thick coating, characterized by that after a cationic electrodeposition coating is coated and cured by heating, an intermediate coating, comprising polymerizable unsaturated compound, photopolymerization initiator, thermal polymerization initiator, and further optionally pigment and/or polyester resin and crosslinking agent, is coated, and the coating film is cured by irradiation with an actinic ray, and then a thermocurable top coating is coated and cured by heating, is disclosed.