PURPOSE: To make mountable only with one tension band bondage tool to various Braun tubes different in size, by changing the preheated temperature at tension band mounting and by opposing with the glass breakdown force at implosion after mounting.

CONSTITUTION: A plurality of heaters 41 are placed at the external wall of the tension band 24 of the bondage unit 2, and one band bondage tool 31 is placed. Further, if the band 24 is extended by at with the operation of one heater 41, the extension by n sets of heaters is nat and the amount of coutraction at cooling of the band 24 can be changed. Accordingly, if n is set to the Braun tubes different in size, the residual tension of the band 24 after mounting and cooling can be corresponded to the decay force of glass caused implosion.