A process for producing a flexible printed circuit board comprising a metallic foil and a polyimide is provided, which comprises coating a metallic foil with a resin solution prepared by adding a tertiary amino compound to a solution of a polyamic acid (a polyimide precursor) represented by the following general formula (I): ##STR1## followed by the imidization thereof, the amount of said tertiary amino compound added to the solution being 10 to 50 parts by weight per 100 parts by weight of solid polyamic acid contained in said resin solution. According to the present invention, a flexible printed circuit board which is free from curling, wrinkling and warping, and which has excellent heat resistance, electrical characteristics and mechanical properties is provided with a simplified production process.