A polyester resin composition and a molded body formed from the polyester resin composition are provided. The polyester resin composition includes a layered silicate and a crystalline polyester. The layered silicate is ion exchanged with a dimethyldialkylammonium salt and the ion exchange amount is equal to or higher than 0.7 and less than 0.9 based on an ion exchange capacity of the layered silicate. The dimethyldialkylammonium salt may be a dimethyldioctadecylammonium salt or a dimethyldidodecylammonium salt.