Iwao Oba made a detailed research in relics pertaining to ancient religious rites in Japan. Was appointed chairman of the committee that was formed to investigate the ruins of Hiraide in Nagano Prefecture (1950-1953). He was also deputed to make research in the ruins of Toro in Shizuoka Prefecture (1943). Among his works are "An Outline of Archaeology in Japan" and "On Shinto Archaeology."