The high frequency induction heating unit which adopted transistor inverter of our own development is widely used for all the fields including the metallic industry, the automatic car industry, the electric and electronic industry, the medical industry and is playing an active part in world every country in addition to Japan.  Also, it is adaptable to safety’s improvement and the efficientization of the work and it is useful for the environment and energy-saving.  It is convinced that the use and the application of this technique become increasingly more important with future industry.