| 摘要 |
PROBLEM TO BE SOLVED: To prevent the top heat insulator of a heater from being cracked or broken by suppressing or preventing a top board from being warped and deformed downward. SOLUTION: A heater 10 having a cylindrical heat insulator 11 is installed around a vertical treatment container 2 housing a large number of objects W to be treated, the outer periphery of the cylindrical heat insulator 11 is covered by outer coating 30, a top heat insulator 13 is provided on the upper part of the cylindrical heat insulator 11, and the upper part of the top heat insulator 13 is covered by a top board 31 linked with the outer coating 30. The top board 31 is composed of a plurality of concentrically divided pieces 31a, 31b and 31c and formed so that the outer diameter of a smaller diameter side divided pieces between the adjacent divided pieces can be larger than the inner diameter of a larger diameter side divided piece, and the smaller diameter side divided pieces are overlapped on the larger diameter side divided pieces in order.
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