An endoscopic surgical apparatus capable of appropriately and easily performing an attaching operation of an endoscope to a mantle tube. An outer tube 300 that penetrates the body wall and is inserted into the body cavity and guides the endoscope and the treatment tool into the body cavity includes a slider 400 that is an interlocking member that moves the endoscope and the treatment tool together to move forward and backward. . When the endoscope for connecting the endoscope insertion portion 102 to the slider main body 402 of the slider 400 is mounted, the large-diameter portion 140 provided in the endoscope insertion portion 102 contacts the proximal end surface 302 of the outer tube 300. The endoscope insertion part 102 is inserted to the position. Thereby, the slider main body 402 can be connected to a predetermined suitable position of the endoscope insertion portion 102.外套管への内視鏡の装着作業を適切且つ容易に行うことができる内視鏡用外科手術装置を提供する。体壁を貫通して体腔内に挿入され内視鏡及び処置具を体腔内に案内する外套管３００は、内視鏡と処置具とを連動させて進退移動させる連動部材であるスライダ４００を備える。そのスライダ４００のスライダ本体４０２に内視鏡挿入部１０２を連結させる内視鏡の装着時において、内視鏡挿入部１０２に設けられた大径部１４０が外套管３００の基端面３０２に当接する位置まで内視鏡挿入部１０２を挿入する。これにより、スライダ本体４０２を内視鏡挿入部１０２の予め決められた好適な位置に連結させることができる。
