The endoscopic surgical apparatus (10) has a mantle tube (300) and an inner needle (600). The mantle tube (300) has an endoscope insertion passage (306) and a treatment instrument insertion passage (308). The inner needle (600) has a short hand portion (610) inserted into the endoscope insertion passage (306) and a long needle portion (602) inserted into the treatment instrument insertion passage (308). During the endoscopic surgical operation, the inner needle (600) is attached to the mantle tube (300). At this time, the distal end portion (614) of the short hand portion (610) protrudes distally from the distal end opening (312) of the endoscope insertion passage (306), and the distal end portion (606) of the long hand portion (602) And projects to the distal side from the distal end opening (316) of the passage (308). By puncturing the distal end portion (606) of the long hand portion (602) on the body wall, the mantle tube (300) is inserted into the body cavity. The cutting edge portion (650) of the front end portion (614) of the short hand portion (610) and the cutting edge portion (634) of the front end portion (606) of the long needle portion (602) are disposed along the same straight line . Therefore, the load when inserting the mantle tube (300) into the body cavity is small.内視鏡用外科手術装置(10)は外套管(300)及び内針(600)を有する。外套管(300)は内視鏡挿通路(306)及び処置具挿通路(308)を有する。内針(600)は、内視鏡挿通路(306)に挿入される短針部(610)及び処置具挿通路(308)に挿入される長針部(602)を有する。内視鏡下外科手術の際、内針(600)は外套管(300)に装着される。このとき、短針部(610)の先端部(614)は内視鏡挿通路(306)の先端開口(312)から先端側に突出し、長針部(602)の先端部(606)は処置具挿通路(308)の先端開口(316)から先端側に突出する。長針部(602)の先端部(606)を体壁に穿刺することにより、外套管(300)は体腔内に挿入される。短針部(610)の先端部(614)の切刃部(650)と、長針部(602)の先端部(606)の切刃部(634)とは、同一直線に沿って配置されている。このため、外套管(300)を体腔内に挿入する際の負荷が小さい。
