International technical cooperation activities of the Institute for Science of Labour in the Showa Period from 1939 to 1987 were reviewed and discussed. There were five distinct activities. First, before and during the World War II, two research offices of the institute were opened in the north-eastern part of China and carried out a wide range of studies to realize humanistic working conditions of Chinese, Russian and Japanese workers, such as farming methods, workers’ foods and nutrition, adaptation to severe cold climate, or work organization of miners. Second, after the War, in 1956, Dr Gito Teruoka, the First Director of the Institute, advocated the regional cooperation in occupational health and organized the First Asian Confer lasting Asian Association of Occupational Health. Third, the Institute collaborated with the ILO and the WHO in their projects, such as fragmented jobs in offices in 1979, developments of an action-checklist for improving working conditions and environments in the Philippines and also through the staff dispatch to the ILO. Fourth, the Institute contributed to shaping and implementing JICA’s occupational health promotion projects in the Republic of Korea in the 1970s through the staff dispatch and receiving fellow researchers, and also to the silicosis prevention project in Peru. Fifth, the Institute participated in a Japanese medical expert mission to the Republic of China in 1957 for establishing a collaborative relationship and later received Chinese fellow researchers to the Institute. These serial international activities built the foundation for developing Asian regional cooperation in work science and occupational health fields.