PURPOSE: To enhance a person's safety upon interruption of power supply to a hyperthermia device used for warming treatment by providing a physical separation means to release electromagnetic attraction state between a retaining plate and a guide member for enabling the device to be operated with an external switch.

CONSTITUTION: An electromagnet 5 to lose a magnetic force at the time of power supply attaches to a guide case 3 in operation state (i.e., at the time of power interruption), thereby fixing an arm 1. When a switch 8 is pressed, a manually operated valve 6 opens due to hydraulic pressure in a spiral tube 8, and a cylinder 9 expands due to pneumatic pressure in an air tank 7. According to this construction, the electromagnet 5 is separated from the guide case 3, thereby releasing the arm 1.