This endoscopic surgical device (10) is provided with a mantle tube (300) and an inner needle (600). The mantle tube (300) is provided with an endoscope insertion passage (306) and a treatment-tool insertion passage (308). The inner needle (600) is provided with a short needle part (610) which is inserted into the endoscope insertion passage (306), and a long needle part (602) which is inserted into the treatment-tool insertion passage (308). During endoscopic surgery, the inner needle (600) is fitted to the mantle tube (300). At this time, the tip (614) of the short needle part (610) protrudes towards the tip side from a tip opening (312) of the endoscope insertion passage (306), and the tip (606) of the long needle part (602) protrudes towards the tip side from a tip opening (316) of the treatment-tool insertion passage (308). The mantle tube (300) is inserted into a body cavity as a result of the tip (606) of the long needle part (602) puncturing a body wall. A cutting blade part (650) of the tip (614) of the short needle part (610) and a cutting blade part (634) of the tip (606) of the long needle part (602) are disposed along the same straight line. As a result, the load when the mantle tube (300) is inserted into the body cavity is small.Ce dispositif chirurgical endoscopique (10) est pourvu d'un tube d'enveloppe extérieure (300) et d'une aiguille interne (600). Le tube d'enveloppe extérieure (300) est pourvu d'un passage d'insertion d'endoscope (306) et d'un passage d'insertion d'outil de traitement (308). L'aiguille interne (600) est pourvue d'une courte partie d'aiguille (610) qui est insérée dans le passage d'insertion de l'endoscope (306), et d'une longue partie d'aiguille (602) qui est insérée dans le passage d'insertion de l'outil de traitement (308). Lors d'une intervention de chirurgie endoscopique, l'aiguille interne (600) est montée sur le tube d'enveloppe extérieure (300). A ce moment, la pointe (614) de la courte partie d'aiguille (610) fait saill
