Method for forming a paint film

A method for forming a multilayer paint film comprising the steps of forming an uncured film on a substrate with a cationically electrodepositable paint on a substrate, further coating an aqueous paint on the uncured film of the electrodeposited film in a wet-on-wet manner, and then curing with heating the both films,

• wherein (i) the electrodeposited film of the cationically electrodepositable paint has a film weight reduction after curing with heating of 10% by weight or less, the cationically electrodepositable paint comprising
• (A) a resin having hydroxyl groups and cationic groups, and
• (D) a blocked polyisocyanate compound being blocked with a blocking agent having a molecular weight of 130 or less as principal components;
• wherein (ii) the aqueous paint is composed mainly of
• (a) a polyester resin optionally modified with a urethane and having an acid value within the range of 10 to 100 and a hydroxyl value within the range of 20 to 3000;
• and
• (b) a water-soluble or -dispersible amino resin having an imino group.