A method of purification of an oligoaniline compound which comprises the steps of: dissolving an oligoaniline compound represented by the formula below in a solvent, thereby giving a solution containing the oligoaniline compound, the oligoaniline compound - being crude oligoaniline compound as produced, or - containing oligoaniline in oxidised form and having an absorption coefficient ε at a wavelength of 560 nm of from 80 to 1000; treating the solution with activated carbon in an amount of 4 to 20 wt% based on the amount of the oligoaniline compound; removing the activated carbon, and performing recrystallisation, thereby obtaining a purified oligoaniline compound represented by formula which has an absorption coefficient ε at a wavelength of 560 nm no higher than 30: where R 1, R 2, and R 3 independently denote hydrogen, hydroxyl group, halogen group, amino group, silanol group, thiol group, carboxyl group, sulfonic group, phosphoric group, phosphate group, ester group, thioester group, amide group, nitro group, monovalent hydrocarbon group, organooxy group, organoamino group, organosilyl group, organothio group, acyl group or sulfonyl group; and A and B independently denote divalent groups of formula or below: where R 4 to R 11 independently denote hydrogen, hydroxyl group, halogen group, amino group, silanol group, thiol group, carboxyl group, sulfonic group, phosphoric group, phosphate group, ester group, thioester group, amide group, nitro group, monovalent hydrocarbon group, organooxy group, organoamino group, organosilyl group, organothio group, acyl group or sulfonyl group; m and n independently denote integers equal to or larger than 1 such that m + n ≤ 20. dissolving an oligoaniline compound represented by the formula below in a solvent, thereby giving a solution containing the oligoaniline compound, the oligoaniline compound - being crude oligoaniline compound as produced, or - containing oligoaniline in oxidised form and having an absorption coefficient ε at a wavelength of 560 nm of from 80 to 1000; - being crude oligoaniline compound as produced, or - containing oligoaniline in oxidised form and having an absorption coefficient ε at a wavelength of 560 nm of from 80 to 1000; treating the solution with activated carbon in an amount of 4 to 20 wt% based on the amount of the oligoaniline compound; removing the activated carbon, and performing recrystallisation, thereby obtaining a purified oligoaniline compound represented by formula which has an absorption coefficient ε at a wavelength of 560 nm no higher than 30: where R 1, R 2, and R 3 independently denote hydrogen, hydroxyl group, halogen group, amino group, silanol group, thiol group, carboxyl group, sulfonic group, phosphoric group, phosphate group, ester group, thioester group, amide group, nitro group, monovalent hydrocarbon group, organooxy group, organoamino group, organosilyl group, organothio group, acyl group or sulfonyl group; and A and B independently denote divalent groups of formula or below: where R 4 to R 11 independently denote hydrogen, hydroxyl group, halogen group, amino group, silanol group, thiol group, carboxyl group, sulfonic group, phosphoric group, phosphate group, ester group, thioester group, amide group, nitro group, monovalent hydrocarbon group, organooxy group, organoamino group, organosilyl group, organothio group, acyl group or sulfonyl group; m and n independently denote integers equal to or larger than 1 such that m + n ≤ 20.