Method of producing ultraviolet radiation absorbent

An ultraviolet radiation absorbent is produced by a method including specified Step A, Step B and Step C. Step A is a process of causing an amidation of anthranilic acid and terephthaloyl dichloride in the presence of a solvent and an alkali to generate N,N′-bis(o-carboxyphenylterephthalamid) and separating a solid component containing N,N′-bis(o-carboxyphenylterephthalamid) generated by this amidation. Step B is a process of separating a solid component containing cyclic imino ester compound of a specified kind. Step C is a process of processing the solid component separated in Step B with an alkaline solution and further washing with water to obtain the ultraviolet radiation absorbent for thermoplastic polymers containing cyclic imino ester compound of the specified kind.