A process for forming a metallic paint film comprising(a) coating on a substrate surface a metallic paint containing as a vehicle component a modified vinyl-type copolymer obtained by copolymerizing 5-75 weight % of cellulose acetate butyrate with 95-25 weight % of a monomeric component consisting of one or more vinyl-type monomers,(b) if necessary, coating a thermosetting resin-type clear topcoating while said coated metallic paint film is in the unhardened state and(c) then baking the paint film.