A coating film-forming method that includes a first step that involves coating a cationic electrodeposition coating composition (A) containing an electrically conducting agent, followed by washing with water and heat curing and drying to form a cured cationic electrodeposition coating film. A second step that involves coating such an anionic electrodeposition coating composition (B). The coating film formed therefrom has a chromatic color or a white color as an achromatic color onto the cured cationic electrodeposition coating film. This is followed by washing with water, and removing water by preheating or air blowing to form a non-cured anionic electrodeposition coating film. A third step that involves coating a topcoating composition (C) thereonto to form a non-cured topcoating film, and heat curing and drying a resulting laminated coating film simultaneously.