PURPOSE: To form a colored paint coated film having excellent adhesion to a hard coating layer by coating a specific pretreating agent on a hard coating layer which is formed on the surface of a base body and consists essentially of polysiloxane.

CONSTITUTION: A hard coating layer which is a material to be painted consists essentially of polysiloxane. A silane or siloxane having a substd. or unsubstd. amino group bonded with a silicon atom via at least one carbon atom or an alkoxy group bonded with a silicon atom is diluted with a volatile siloxane and is coated as a pretreating agent for coating a synthetic resin paint on the hard coating layer. The coating film after coating is thoroughly dried at an ordinary temp. and is dried by a heat treatment and finally a colored paint coated film of acrylic lacquer or the like is formed.