It is possible to move the insertion part of the endoscope inserted into the mantle tube and the insertion part of the treatment tool in the axial direction, and even when the insertion part of the treatment tool is moved finely in the axial direction, there is no vibration A good endoscopic image. When the operation amount of the endoscopic surgical apparatus 1 exceeds the play amount t during the operation in the insertion / extraction direction of the treatment instrument 50, the endoscope 10 moves in the insertion / extraction direction in conjunction with the movement in the insertion / extraction direction of the treatment instrument 50. Moving. Further, the treatment instrument 50 moves in the axial direction of the outer tube 100 with a play amount t with respect to the endoscope 10. Therefore, when the treatment tool 50 is moved in the insertion / removal direction, the endoscope 10 does not move in the insertion / removal direction as long as the movement is within the range of the play amount t. By providing such a play amount t, fine movement of the treatment tool is not transmitted to the endoscope.外套管に挿入された内視鏡の挿入部と処置具の挿入部とを軸方向に連動して移動でき、かつ処置具の挿入部を軸方向に細かく移動させた場合でも、揺れのない良好な内視鏡撮影画像を得る。内視鏡手術装置１は、処置具５０挿抜方向の操作時に、遊び量ｔを超えて操作された場合には、処置具５０挿抜方向の移動に連動して、内視鏡１０が挿抜方向に移動する。また、処置具５０は内視鏡１０に対し、遊び量ｔをもって外套管１００の軸方向に移動する。よって、処置具５０を挿抜方向に移動させたとき、遊び量ｔの範囲内の移動であれば、内視鏡１０は挿抜方向に移動しない。このような遊び量ｔを備えることによって、処置具の細かな移動は内視鏡に伝達しない。
