A multi-layer paint film satisfies paint film performance, such as water resistance, impact resistance and the like, required of an automobile paint film and which has excellent paint film appearance is obtained. The method comprises coating an aqueous first base paint (A) over an electrodeposited cured paint film to form a first base paint film, and then coating an aqueous second base paint (B) over the first base paint film without carrying out preliminary drying by heating after forming the first base paint film to form a second base paint film, preliminary drying by heating is carried out after forming the second base paint film, coating a single-liquid type clear paint (C) over the second base paint film to form a clear coat paint film. These three paint film layers are heated and cured at the same time.