The present invention relates to a thermoplastic resin composition, which achieves barrier properties against various types of gases, while maintaining flexibility, and a molded body comprising the same. The thermoplastic resin composition of the present invention is characterized in that it comprises an aliphatic polyamide, a semi-aromatic polyamide, and an impact modifier, wherein at least a part of the impact modifier is dispersed in the semi-aromatic polyamide, in the semi-aromatic polyamide, the molar ratio between diamine units and dicarboxylic acid units (the number of moles of diamine units/the number of moles of dicarboxylic acid units) is in the range of 0.97 to 1.02, and the mass ratio of the impact modifier to the total mass of the semi-aromatic polyamide and the impact modifier is in the range of 5% to 15%.