The pitting corrosion resistance and passive film properties of Fe–18Cr–10Mn–(0.39–0.69)N–(0–0.38)C alloys were investigated. The combined addition of carbon and nitrogen enhanced the resistance against pitting corrosion of the alloys, which was attributed to an improvement in the protective ability of the passive film. Both passive film thickness and chromium content in the film were increased along with the sum of carbon and nitrogen content, which was confirmed by the galvanostatic reduction test, Mott–Schottky analysis and X-ray photoelectron spectroscopy measurement.