When the bending wheel 41, the motor 32, the housing case 11, the case attachment/detachment fixing portion 12, and the second bending up/down fixing lever 3h are located at positions other than the release position, they are prevented from being fitted into the lever recess 25. An attachment regulation member 21 that regulates attachment of the housing case 11 to the sub operation portion 3S.湾曲ホイール４１と、モータ３２と、収容ケース１１と、ケース着脱固定部１２と、第２湾曲上下固定レバー３ｈが解除位置以外の位置にある場合に、レバー用凹部２５に嵌入することを妨げて副操作部３Ｓに収容ケース１１を取り付けることを規制する取り付け規制部材２１と、を具備する。
