An endoscope insertion support tool includes an advancing and retracting member that is disposed in an insertion section of an endoscope, capable of advancing and retracting in a hollow passage, a distal end portion of which communicates with the outside, and has length projected from a distal end of the insertion section, a balloon member that includes an attaching portion attachable to an outer surface side of the insertion section of the endoscope and is connected to the distal end of the advancing and retracting member and capable of projecting from the distal end of the insertion section according to an advancing and retracting movement of the advancing and retracting member, and a fluid supplying and discharging unit including a conduit that is connected to the balloon member and inflates and deflates the balloon member according to supply and discharge of a fluid to and from the balloon member.