PURPOSE: To reduce the heater load while cutting down the maintenance coat as well as the attaching and detaching work time by a method wherein a tapered heating frame is spirally trenched and heaters are wound up around the trench to be stuck thereto using a heater press.

CONSTITUTION: The outer periphery of the frame 2 heating a specimen 1 is tapered while a heater containing trench 5 is spirally cut in the tapered part. At this time, the heaters 4 and a heater press 3 in the same taper structure as that of the heating frame 2 are provided. When the heater press 3 is fitted to the heating frame 2, the adherence between the heaters 4 pressed against the heating frame 2 and the heating frame 2 itself can be enhanced. Through these procedures, the heat generated by the heaters 4 can be effectively conducted to the heating frame 2 even in vacuum or low pressure gas atmosphere thereby enabling the heat conductivity to the specimen 1 to be enhanced.