Disclosed is a photosensitive ink which can form a coated film that is excellent in insulation properties, heat resistance, low warping, low elasticity and adhesion with the substrate, when used as an ink for screen printing, and with which clogging of the screen, bleeding, blur, chipping and the like are unlikely to occur even when the screen printing is repeatedly carried out, so that which has an excellent ease of handling in printing. The ink composition comprises 100 parts by weight of an organic solvent-soluble polyimide block copolymer(s), and 1 to 100 parts by weight of a photoacid generator(s). The polyimide block copolymer(s) and the photoacid generator(s) are dissolved in an organic solvent. The polyimide block copolymer(s) contain(s) in its molecular skeleton a diamine having a siloxane bond, and an aromatic diamine having a hydroxyl group(s) and/or carboxyl group(s) at ortho-position with respect to an amino group.