Provided are an overtube and an endoscopic surgical device that can remove foreign matter adhering to an observation window of an endoscope, with a simple operation, and can always guarantee an excellent field of view. A distal end of an endoscope insertion passage 306 through which the endoscope insertion part 102 of an overtube 300 is inserted is provided with a fluid supply and discharge port 500 for delivering cleaning water. In a case where an observation window of the endoscope insertion part 102 inserted through the endoscope insertion passage 306 is cleaned, an operator can set a distal end surface 114 at a predetermined positioning position using a positioning mechanism, without extracting the endoscope insertion part 102 from the endoscope insertion passage 306. Accordingly, a concave cleaning storage part 502 that communicates with the fluid supply and discharge port 500 on a distal end side of the distal end surface 114 of the endoscope insertion part 102 is formed inside the endoscope insertion passage 306 on the distal end side thereof. In this state, cleaning water is supplied from the fluid supply and discharge port 500, cleaning water is stored in the cleaning storage part 502, and foreign matter of the observation window is removed. Subsequently, the cleaning water stored in the cleaning storage part 502 is suctioned from the fluid supply and discharge port 500, and waterdrops are removed from the observation window.
