Abstract
The plot plan of the Itsukushima shrine has been recognized as a design of high originality worldwide. It paid attention to the Torii of Itsukushima shrine by this research. Why was shrine maintained soundly until today though it was the bad building condition of the sea? The design that it is resistant to the earthquake and it doesn't rise though it is on the sea has the structure of the Torii done in RYOBU TORII. Furthermore, Cinnamomum camphora who was resistant to the water had the material of the Torii used, and vermilion which was a traditional surface protection material was given to it. It made the most of the technology of Shiguchi which Japanese traditional technique of at the time of the repair big project of Showa 25-27.
