Provided is a thermoplastic resin composition for the inner liner of pneumatic tires, which has low air permeability and a small percent change in air permeability from fatigue. A thermoplastic resin composition obtained by dispersing a modified rubber having an acid anhydride group or an epoxy group into a polyamide resin and an ethylene vinyl alcohol copolymer, the thermoplastic resin composition being characterized in that the ratio of the polyamide resin to the ethylene vinyl alcohol copolymer is between 47/53 and 61/39. The percent change in air permeability of the thermoplastic resin composition in the present invention when subjected 1 million times to 20% elongation strain at room temperature is 1.30 times or more. Additionally, a pneumatic tire using a film comprising the thermoplastic resin composition in the present invention as an inner liner has a percent change in air leakage of 1.30 times or less at room temperature after going 70,000 km.