Disclosed is a method for producing a thermoplastic resin composition, the method including a first step of melt-kneading 100 parts by weight component (A) and from 15 to 200 parts by weight of component (B) to form a melt-kneaded material, and a second step of melt-kneading from 35 to 2300 parts by weight of additional component (B) with the melt-kneaded material formed in the first step, wherein component (A) is an elastomer having a melt viscosity, as measured at a temperature of 230° C. and a shear rate of 121 sec−1, of 1500 Pa·s or more and the component (B) is a polyolefin resin.