Endoscope insertion support tool and endoscope device

An endoscope device comprising:

• an endoscope including a slim insertion section that is insertable into a body cavity and is provided with an illumination window and an observation window at a distal end surface of at a distal end portion of the endoscope;
• an advancing and retracting member that is inserted through a channel disposed in the insertion section to be capable of advancing and retracting in the channel, a distal end side of the advancing and retracting member being capable of projecting from a distal end opening of the channel;
• a balloon member that includes an attaching portion capable of attaching a cylindrical inner peripheral surface of the balloon member to an outer peripheral surface of the insertion section on a distal end side thereof including at least a distal end portion, over a substantially whole length of the balloon member when the advancing and retracting member is maximally retracted, the balloon member being 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 movement of the advancing and retracting member;
• and
• 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 with a diameter of the cylindrical inner peripheral surface of the balloon member maintained.