The purpose of the present invention is to provide: a thermoplastic resin composition which exhibits excellent rigidity, while having excellent impact strength characteristics; and a method for producing the thermoplastic resin composition. This thermoplastic resin composition, wherein a polyolefin resin contains a polyamide resin that is dispersed therein, is characterized in that: the thermoplastic resin composition is obtained by melting and kneading a polyolefin resin and a mixed resin that is obtained by melting and kneading a polyamide resin and a compatibilizer; and the compatibilizer is a modified elastomer that is obtained by providing an elastomer (such as an olefin-based thermoplastic elastomer or a styrene-based thermoplastic elastomer) with a reactive group that is reactive with the polyamide resin. The present invention also relates to a thermoplastic resin composition which is obtained by melting and kneading from 1% by mass to 80% by mass (inclusive) of a plant-derived polyamide resin such as polyamide 11, from 5% by mass to 75% by mass (inclusive) of a polyolefin resin and from 1% by mass to 30% by mass (inclusive) of a compatibilizer that is an olefin-based thermoplastic elastomer that is modified with an acid.