<p>Recently, aging of infrastructures constructed in large amount during high economic growth period is becoming one of social problem. Because water is necessary for almost of all deteriorations of concrete structures, organic coating materials are often used for preventing water. It is well known that organic coating materials are deteriorated by ultra-violet ray with time, and accelerated weathering test is carried out for evaluating weatherability of coating materials. However, details of deterioration mechanism of organic coating materials are still unclear and relationship between weathering test and deterioration by sunlight is not made clear. Therefore, quantitative evaluation method of deterioration of organic coating materials has not been established so far. Then in this study, Raman spectroscopy is focused on as an available method in fields, it was tried to develop deterioration index of organic coating materials with Raman spectroscopy. As results, it was made clear that fluorescence increases with propagation of UV deterioration because carbonyl turn into carboxyl due to deterioration. And deterioration of organic coating materials can be evaluated by using photobleaching of fluorescence peak in Raman spectrum.</p>