Herein is provided a color filter prepared by providing red, green and blue image elements, comprising as photosensitive resin and a pigment, and a black matrix on a transparent substrate and further providing thereon a transparent electrode layer, wherein said photosensitive resin is so formulated that it comprises a polyfunctional acrylate monomer, an organic polymer binder and a photopolymerization initiator comprising a 2-mercapto-5-substituted thiadiazole compound represented by general formulas (I) and/or general formulas (II), a phenyl ketone compound represented by general formulas (III) and 2,4,5-triphenylimidazolyl dimer composed of two lophine residues combined to each other through intermediation of a single covalent bond.A pattern having a high precision and a good surface smoothness can be obtained owing to the photosensitive resin, and a color filter having a good environmental resistance can be obtained owning to the pigment.