We have been conducting research and development of the DC induction heating device of aluminum billet using HTS magnets. In this R&D, following the development of main components such as the HTS magnet system, the heating control system and the mechanism for grasping and rotating the aluminum billet, the demonstration device for 400 kW-class billet heater was developed and the heating power of over 400 kW was demonstrated. In this study, as the final step of the R&D, we conducted a continuous repetitive heating test and evaluation of the electromagnetic and mechanical influence due to the heating operation on the HTS coil.It was demonstrated that the continuous repetitive heating of 90 billets (more than two hours) with the rated power was possible. The temperature increase and the behavior of mechanical stress of the HTS coil during the continuous heating operation were evaluated.It was confirmed that the soundness of the HTS coil through the continuous repetitive heating was not compromised.