"Shasoh" is the peculiar forest spaces in Japan. The objective of our study is to make clear the meanings, significance, evaluations, and transition of Shasoh in a process of legislation of National Monuments. The period of research was from the Meiji Era to the early Syowa, and research method was using the journals named National Monuments to examine how they recognized the preservation system for national monuments. In the early period, it was observed that Shasoh was recognized not only as the forests with excellent scientific value but also as the space implying the combined value. Additionally, some of Shinto shrines were abolished and others were merged by government in this age. The research detected in those journals and other articles that SHIRAI Mitsutaro emphasized the value of Shasoh against that. However, the point of view to see the meaning of complicated values with Shasoh has vanished, on the other hand, Shasoh has become to be recognized as the place of botanical meanings.