Bacteria with ability for iron reduction in the soil can use corrosion products of iron remains as energy source. The activities of this bacteria cause the change of corrosion products. As a result, it can be difficult to identify corrosion products promoting corrosion of iron remains. The purpose of this study, is to investigate the change in corrosion products that bacteria causes and to improve understanding about the corrosion of iron remains. To simulate corroded condition of excavated iron remains, carbon steel corroded by solution of NaCl and Na2SO4 was prepared. Then the prepared carbon steel was immersed in a liquid medium with bacteria. The incubation period was 42days. After experiment, the carbon steel was analyzed by SEM-EDS, X-ray diffraction method. The result is that the carbon was changed to green because of activity of bacteria and that the plate crystal and lozenge crystal were generated on the corrosion specimen. Also, we confirmed that the activities of bacteria differenciated colors and forms of corrosion products.