Recently, Reinforced Concrete(RC) is used in most buildings. However, steel bars in concrete cause corrosion through carbonation. Furthermore, corrosion shortens the life span of RC structures. Therefore, the surface-finishes such as restraint for penetration and diffusion of CO2 were used to lengthen the life span of RC structures. This study attempted to verify the restraining effect on a carbonation job according to the applied surface-finishes using an FEM analysis. This study also evaluated the restraining effect of carbonation on other surface-finishes with the process proposed in this study.