To provide the novel method for forming a double-layer coating film with the finished appearance and interlayer adhesion improved, low in VOC and with the coating stage shortened.

A cationic electrodeposition coating material A is applied, a water-base intermediate coating material B contg. a block isocyanate compd. as a cross-linking agent is applied on the uncured face, both coating films of the coating materials A and B are cured by heating, then a colored overcoating material C and a transparent coating film forming water-base overcoating material D contg. an acrylic resin, an epoxy group-contg. compd., ≥1 kind of compd. selected from secondary and tertiary amines and a cross-linking agent are successively applied and heated to cure both coating films of the coating materials C and D, and further a clear coat E is applied on the cured coated face, heated and cured.