There is provided an endoscopic surgery device which can easily acquire an image desired by a surgeon and has high operability. The endoscopic surgery device includes: an outer tube body 302 that penetrates through a body wall to be inserted into a body cavity； an endoscope insertion path 304 provided inside the outer tube body 302； a treatment tool insertion path 306 provided inside the outer tube body 302； a position sensor 310 that has a non-sensitive area where no change in a relative position of the treatment tool insertion part 202 with respect to the endoscope insertion part 102 is detected even if the treatment tool insertion part 202 is moved back and forth, and a sensitive area that is an area other than the non-sensitive area, where change in a relative position of the treatment tool insertion part 202 is detected when the treatment tool insertion part 202 is moved back and forth, and that detects a movement amount of the treatment tool insertion part 202 with respect to the outer tube body 302 in the sensitive area； and a control unit 314 that changes a range of an observation image acquired by the endoscope 100 in accordance with the movement amount detected by the position sensor 310.
