Ni-Ti alloys have been investigated for applying to various surgical procedures. However, little is known about the toxicity of Ni-elements and the actual conditions of surface modification of Ni-Ti alloy for preventing the toxicity of Ni. In this study, the corrosion resistance of Ni-Ti alloys was improved through making TiO2 thin film by conducting in air oxidation and reactive sputtering. These thin films were characterized using FE-SEM, XRD, XPS and AFM. And judging from the polarization curves obtained by electro-chemical measurement in quasi-living body environment, corrosion resistance of Ni-Ti super elastic alloy was evaluated. From these considerations, some trials for establishing a method for TiO2 thin film formation on the surface of Ni-Ti alloy were conducted from the view point of improving biocompatibility.