In a configuration in which the endoscope can be moved forward and backward in conjunction with the advancement and retraction of the treatment instrument, the distal end of the treatment instrument can be easily confirmed while reducing the diameter of the outer tube, improving the surgical efficiency. The present invention provides an endoscopic surgical apparatus and a mantle tube capable of achieving the above. The outer tube 300 inserted into the body wall can be inserted with the endoscope insertion portion 102 of the endoscope and the treatment tool insertion portion 202 of the treatment tool, and includes a slider that moves forward and backward in conjunction with them. Is done. The endoscope insertion portion 102 is guided in the direction away from the distal end of the treatment instrument insertion portion 202 in the vicinity of the endoscope delivery port 312 through which the endoscope insertion portion 102 is led out at the distal end cap 360 of the outer tube 300. A guide portion 384 is provided, and the endoscope insertion portion 102 is led out from the endoscope payout opening 312 in an oblique direction.処置具の進退移動に連動して内視鏡を進退移動可能とした構成において、外套管の細径化を図りつつ、処置具の先端の状態を容易に確認することができ、手術効率の向上を図ることが可能な内視鏡用外科手術装置、及び外套管を提供する。体壁に刺入される外套管３００には、内視鏡の内視鏡挿入部１０２と処置具の処置具挿入部２０２とが挿通可能であり、それらを連動させて進退移動させるスライダが具備される。外套管３００の先端の先端キャップ３６０において内視鏡挿入部１０２を導出する内視鏡繰出口３１２の近傍には、処置具挿入部２０２の先端から離れる方向に内視鏡挿入部１０２を案内するガイド部３８４が設けられ、内視鏡挿入部１０２が内視鏡繰出口３１２から斜め方向に導出される。
