The present invention provides a plastic substrate, including: a polyimide film; a hard coating layer formed on one side of the polyimide film; and a transparent electrode layer formed on the other side of the polyimide film. The plastic substrate has excellent light transmittance high hardness characteristics, superior ITO processability and flexibility. Further, the plastic substrate can function as both a window film and an electrode film when it is applied to a touch screen panel. Thus, the present invention provides a touch screen panel which can be slimmed by reducing the number of laminated films including the plastic substrate.