In carbon dioxide capture and storage, CO2 emitted from various industries containing impurities is captured and injected underground in dense or supercritical phase through tubings. In order to evaluate corrosion resistances of materials in the supercritical CO2 with a slight amount of O2, corrosion tests were performed under the conditions of 5 mass% NaCl equilibrium with CO2, containing with the various amount of O2 at total pressure of 130 bar and 100 °C. Super Martensitic Stainless Steel (UNS S41426), Duplex Stainless Steel (UNS S82551), and Super Duplex Stainless Steel (UNS S39274) were evaluated. Localized corrosion was observed in S41426 at conditions higher than 200ppm O2 (0.026 bar O2 partial pressure) condition. On the other hand, S82551 and S39274 showed good corrosion resistance in the same condition. As for S82551, it suffered from localized corrosion at 1000ppm O2 (0.13 bar O2) condition. However, in the actual O2 concentrations, it is considered that S82551 and S39274 are suitable materials even if formation water flow back has occurred.