A method of depositing indium oxide or indium tin oxide thin film on a polymer substrate is disclosed. In the method, oxygen or argon ion beam is radiated on a polymer substrate by a constant accelerating energy in a vacuum state to modify the surface of the polymer substrate, on which an IO thin film or an ITO thin film is deposited while oxygen ion beam, argon ion beam or their mixture ion beam is being radiated in a vacuum state. In addition, ion beam is generated from a cold cathode ion source by using argon, oxygen or their mixture gas and sputtered at a target substance composed of In2O3 or In2O3 and SnO2, thereby an IO or an ITO thin film can be deposited on the surface-modified polymer substrate. |