Disclosed is a production method of a thermoplastic resin composition comprising: compounding 0.001 to 50 parts by mass of a metal complex (B) with respect to 100 parts by mass of a thermoplastic resin (A), and kneading it under a condition of a kneading temperature of 225 to 300° C. and of a kneading time of 0.5 to 20 minutes, wherein a metal of the metal complex (B) is a metal except for zinc; a molded body obtained by molding the thermoplastic resin composition which is obtained by the production method; and a light emission body using the molded body.