Advance and retreat assist tool for endoscopic treatment instrument

An advance and retreat assist tool for an endoscopic treatment instrument, the advance and retreat assist tool comprising:

• a base unit comprising a first hole portion which has a first central axis and a second hole portion which has a second central axis slanted relative to the first central axis and which is in communication with the first hole portion;
• an attachment portion which attaches the base unit to a treatment instrument insertion portion provided in a grasping portion of an endoscope so that a side of the first hole portion having the first central axis faces a treatment instrument insertion hole portion and so that the base unit is rotatable around a central axis of the treatment instrument insertion hole portion;
• a first tubular member provided to have a third central axis which is provided along a direction of the second central axis and is provided coaxially with the second central axis, the endoscopic treatment instrument being inserted into and fixed to the first tubular member;
• a rotary portion into which the first tubular member is inserted and which rotates around the third central axis of the first tubular member;
• and
• an advance and retreat mechanism which converts a rotation force of the rotary portion to an advance and retreat force along a direction of the third central axis of the first tubular member to advance and retreat the first tubular member and endoscopic treatment instrument when the rotary portion rotates while preventing rotation of the first tubular member.