Economic losses due to the corrosion of steel structures in concrete is almost about 4% of GNP. It is almost 70 billion dollars in America. Also, The Korean economy is expected to experience a 4～5% loss in GNP in the near future in by considering the industrial background that has been formed by heavy industries. Although deteriorations in concrete structures demonstrate a high diversity of factors, it finally comes down to the lowering of water resistance performance in structures based on the crack generation due to the corrosive expansion of steel bars. Thus, it is very important to investigate the lowering of water resistance performance in structures according to the level of the corrosion in steel bars.