Abstract: The present invention relates to a method for producing a thermoplastic resin composition by melt mixing Thermoplastic Resin (A) with Thermoplastic Resins (B) and (C) having a lower melting temperature or glass transition point than Thermoplastic Resin (A) by 10.degree. C. or more. The method comprises feeding Thermoplastic Resin (A) containing volatile components having a molecular weight of 300 or less at an amount of 500 to 30,000 ppm and Thermoplastic Resin (B) containing fewer volatile components than Component A from a top supply port of a melt kneader, removing volatile components under reduced pressure, and feeding Thermoplastic Resin (C) from a side supply port. According to the present invention, it is possible to produce a thermoplastic resin composition which satisfies inconsistent properties, i.e., improved impact strength and fewer volatile components, while at the same time having advantages in energy consumption and operation.