Industry-government-university collaboration (IGUC) in Japan during the period from World War II to the postwar time has recently attracted the attention of some historians. However, there are only a few case studies focussing on the development of a specific technology. This paper presents a case history of high frequency (HF) heating and hardening technology from the pre-war to the post-war period in Japan, and examines the role of IGUC for the technological development.Many new technologies were developed during the War, but the most famous and important among them was electronics. It originally led to the development of radio, but thereafter, people tried to apply it in other industrial and technological fields also. The HF heating and hardening technology attracted attention as a promising manufacturing technology after the War. It is one of the reasons for which a lot of idle HF valve oscillators for military use were applicable to HF heating equipments.Consequently, this paper gives a clear picture that the network of IGUC expanded from the pre-war to the post-war period in the field of HF heating technology. In the pre-war period, there was a lack of IGUC because new technologies for Japanese firms were mainly procured from foreign firms. But, the situation changed during the War. Japanese firms needed to develop new technologies by themselves or in collaboration with other domestic institutes. Public research institutes and university professors played an important role in IGUC. As a result of this collaboration, some new enterprises got the opportunity to establish and grow as leaders in the industry.