The corrosion serveys of two steel pipe structures and three steel sheet pile structures have been carried out, by means of specimens cut out from at different depths and locations of each structure on the occasion of reconstruction.
　The concentrated corrosion below M.L.W.L. due to macro-corrosion occured in four structures. The corrosion below M.L.W.L. occured in the structure to which the cathodic protection had been applied, when the cathodic protection was not maintaind adequately.
　In two of structures, pitting corrosion by local corrosion and holes by uniform corrosion occured at above H.W.L.and the maximum corrosion rate there were 0.5mm/y and more than 0.6mm/y. Except such extremely corroded parts, the corrosion rates were fairly small in comparision with the rates being considered in the desinging.