This endoscopic surgical device includes: an endoscope； a treatment tool； and a mantle tube. The inside of the mantle tube is partitioned by a partition wall member provided with an endoscope guide groove and a treatment-tool guide groove, to form an endoscope insertion passage and a treatment-tool insertion passage. An endoscope fixation tool and a treatment-tool fixation tool are respectively disposed inside the endoscope guide groove and the treatment-tool guide groove. The endoscope fixation tool advances and retracts in conjunction with the endoscope insertion part inserted through the endoscope insertion passage. The treatment-tool fixation tool moves in conjunction with the treatment-tool insertion part inserted through the treatment-tool insertion passage. When a coupling ring externally fitted to the partition wall member interlocks the endoscope fixation tool with the treatment-tool fixation tool, the endoscope insertion part also moves in conjunction with the advancement and retraction of the treatment-tool insertion part.
