The present invention discloses a method of producing a modified polyimide comprising a polycarbonate, which modified polyimide has excellent electric properties and adhesion as well as excellent heat resistance, flexibility, bending property, low warping, chemical resistance and storage stability; and the modified polyimide. Also disclosed are a composition comprising the modified polyimide and used thereof. According to the method in which an isocyanate-terminated oligomer comprising a polycarbonate component having excellent flexibility is allowed to react with a tetracarboxylic dianhydride to synthesize a tetracarboxylic dianhydride oligomer comprising the polycarbonate component and the thus obtained oligomer is then further allowed to react with an aromatic diamine and aromatic tetracarboxylic dianhydride to produce a polyimide block copolymer, by selecting the aromatic diamine from a wide range of selectable aromatic diamines, an excellent modified polyimide satisfying all of the above-described various characteristics can be produced.