Provided is a method for producing a resin composition by melt-kneading a cyclic olefin polymer (A) having a glass transition temperature of from 60 to 200° C. and a flexible polymer (B) having a glass transition temperature of 0° C. or lower, wherein a part of the cyclic olefin polymer (A) is previously melt-kneaded with the flexible polymer (B) and a radical initiator (C) and then the remaining cyclic olefin polymer (A) is added thereto and melt-kneaded. The cyclic olefin polymer (A) is divided into two portions and added separately at two times, and accordingly, the mixture having a crosslinked structure may be diluted with the cyclic olefin polymer (A) not having a crosslinked structure, and the increase in the melt viscosity of the resin composition may be thereby prevented. A composition having good abrasion resistance and good melt shapability can be obtained.