An insertion part of an endoscope and an insertion part of a treatment tool, which are inserted in an outer tube, can be synchronously moved in the axial direction, and, even when the insertion part of the treatment tool is slightly moved in the axial direction, an excellent endoscopic image without shake is obtained. When an endoscopic surgery device 1 is operated over an allowance amount t when a treatment tool 50 is operated in an insertion and removal direction of the treatment tool 50, an endoscope 10 moves in the insertion and removal direction in interlock with the movement in the insertion and removal direction of the treatment tool 50. Moreover, the treatment tool 50 moves in the axial direction of the outer tube 100 with the allowance amount t with respect to the endoscope 10. Therefore, when the treatment tool 50 is moved in the insertion and removal direction, if the movement is within a range of the allowance amount t, the endoscope 10 does not move in the insertion and removal direction. By providing such allowance amount t, slight movement of the treatment tool is not transmitted to the endoscope.
