After his involvement in organizing the World Exposition of 1970 held in Osaka, Umesao was instrumental in the founding of the National Museum of Ethnology that opened in the Osaka Expo grounds in 1977. Appointed as head of the museum’s preparatory office in 1974, he set forth his team of young scholars on ethnological expeditions across the globe assembling documentary materials and artifacts. He remained as the director-general of the museum until his retirement in 1993, continuing as museum’s special advisor until his death in 2010.