A plastic substrate and a display device including the same are disclosed. A plastic substrate includes a film including a poly(amide-imide) copolymer and a hard coating layer disposed on one surfaceof the film including the poly(amide-imide), wherein the hard coating layer includes a siloxane copolymer cross-linked through a cross-linkable functional group thereof, and the plastic substrate haspencil scratch hardness of greater than or equal to 2H measured at a vertical load of about 1 kg according to ASTM D3363, transmittance of greater than or equal to about 89 % in about 350 nm to about750 nm wavelength region, and flexural characteristics.