A cylindrical holder 51, a groove 51m balloon band was removed from the outer periphery 30g of the ultrasonic transducer unit 30 is engaged, a cutting portion S for cutting the holding portion 51 from one end to the other end 51p 51q, a fitting portion 60 for the inner peripheral surface 51n composed of radially K in diameter expanding freely member together is reduced in diameter toward the one end from the other end 51p 51q of the holding portion 51, the inner from the peripheral surface 51n of the radial direction K It has and a allusion part 51af~51df the end was allusions of one end of the fitting portion 60 with inwardly projecting.筒状の保持部51と、超音波振動子ユニット30の外周30gから外されたバルーンバンドが係止される溝51mと、保持部51を一端51pから他端51qまで切断する切断部Sと、保持部51の内周面51nを他端51qから一端51pに向けて縮径させるとともに径方向Kに拡径自在な部材から構成された嵌合部60と、内周面51nから径方向Kの内側に突出するとともに嵌合部60の一端側の端部が当てつけられた当てつけ部51af~51dfと、を具備している。
