Operability in inserting an insertion part of an endoscope into a body cavity using an insertion assisting tool is improved. In an insertion assisting tool 60, a sidewall portion of a tube main body 64 through which an insertion part 12 of an endoscope 10 is passed is provided with a sidewall opening part 68 having a size in which the insertion part 12 can pass through. A distal end side of the sidewall opening part 68 is provided with a guiding valve 82, and the insertion part 12 is guided by the guiding valve 82 to be easily fed from the sidewall opening part 68. With swingably supported on the guiding valve 82, when the insertion part 12 is fed from a distal end opening part 67 of the tube main body 64, allowing the parallel state of being substantially parallel to an axial direction of the insertion part 12 and passing the insertion part 12 to a distal end opening part 67 side are enabled.
