The superstructure of a pier, which is a typical port concrete structure, is located in a very severe environment prone to chloride attack. The supply of chloride ion is considered to be reduced by the existence of curtain wall at the berthing side. However, the reduction effect is not estimated quantitatively. In this study, some curtain walls with heights of the different lower end were set in front of the existing superstructure on pier in order to estimate the reduction effect of the chloride ion supply to the concrete under a pier. Also, the concrete specimens were set on the concrete superstructure behind curtain walls, and the chloride ion in concrete was investigated after a few years.
　In the range of this study, it was confirmed that the amount of chloride ion supply to pier superstructure can be reduced by setting the curtain wall lower end height more deeply than L.W.L.+0.5m. By the existence of curtain wall, it was supposed that the short-period wave was reflected partially and the wave height was reduced inside the pier. As this result, the seawater spray was hard to affect the concrete superstructure inside the pier, and the supply of chloride ion was considered to be reduced.