This paper focuses on the use of protective coatings as the means of protecting concrete structures.
　The aim of the research reported here is to gather quantitative data on the performances of several coating systems under the marine environment.
　Main conclusions obtained in this study are as follows;
(1)Concrete surface coating is effective in protecting concrete structures against salt attack.
(2)Some epoxy-based materials show the color-change in coating surfaces from white to yellow.
(3)Electro-chemical measurements of embedded steel are effective in determining corrosion conditions non-destructively.
(4)Colour measurements are effective in quantifying color changes in the coating surface.
(5)In order to make an adequate evaluation of the coating systems, an index of weather resistance and an index of salt resistance are necessary.