This paper aims, with reference to Shibusawa Foundation for Ethnological Studies' Archives, to envisage activities of Japanese Society of Ethnology (1934-2004, later Japanese Society of Cultural Anthropology) in the 1930s through the 1960s. Focusing on its reorganization from a voluntary society into an incorporated foundations (1942), and restoration back to a voluntary society (1964), this paper discussed 1) how its museum-related estates were inherited on occasion of the first reorganization; 2) the society's intention of establishing the museum in 1937; 3) why and how the society was slightly renamed around 1946, and 4) the society's intention of the second reorganization in 1964. As a result, the relevance of museum activities proved to be much larger than the society members had ever estimated. The society was reconciling two different functions as volunteer society and as incorporated foundation, until it transferred the latter to Shibusawa Foundation for Ethnological Studies.