[en] Corrosion is an interaction between the metal and the environment, so that the corrosion behavior of carbon steel overpack might be affected by not only the environmental factors but also the material factors. In this study, the effect of general impurities in carbon steel such as C, Si, Mn, P and S on the electrochemical behavior and the corrosion rate were studied using carbonate aqueous solution and synthetic seawater. The experimental results were summarized as follows; The effect of the impurities on the critical passivation current density, I_p and the passive current density, I_pass were small in 0.01M carbonate aqueous solution at pH 10. Breakdown of passive film and increase in anodic dissolution were observed in the tests for high Si condition of 0.73% and 0.97%. In buffer material saturated with 0.01M carbonate aqueous solution, no passivation was observed and the effect of impurities on the anodic polarization behavior was small. The corrosion rate of carbon steel in seawater was increased with the concentration of impurities. Among the impurity elements, the effects of P and Mn were relatively large. The results of the electrochemical measurement showed that the cathodic reaction was accelerated by the addition of Si, Mn and P respectively in synthetic seawater environment. The amount of corrosion observed in the immersion test in buffer material was also increased by the addition of these elements. (author)