PROBLEM TO BE SOLVED: To provide an endoscope system that enables an insertion part of an endoscope to be cooled, using a guide tube, and enables dirt on an apical surface of the insertion part to be easily removed, and further is excellent in observation properties.SOLUTION: An endoscope comprises: a guide tube 20 an insertion part 10 of the endoscope and an air supply device. At a tip portion of the guide tube 20, an advance direction change part B is formed that changes an advance direction of air A supplied to a space 70 to an interior side in a radial direction K, and in an advance direction change part B, an air discharge port 60K is formed that discharges the air A to the interior side in the radial direction K. When an apical surface of the insertion part 10 is located at an air supply position away by a set distance S1 farther rearward than a tip end 20s, the air A discharged from the air discharge port 60k is supplied to the apical surface.
