Patent ID: 8491463

Claim:
An endoscope treatment system comprising: an endoscope; and a treatment tool that has a sheath configured to be inserted in a channel of an insertion portion of the endoscope; wherein projection portions, that project outward from the sheath in a radial direction, are provided, an engagement portion that engages the projection portions is provided near the channel of the endoscope; the projection portions are exposed outward of the sheath by respectively passing outward of the sheath through a first hole portion, which is formed at a proximal end of the sheath, and the projection portions respectively re-enter into the sheath by passing into the sheath through a second hole portion, which is formed at a distal end of the sheath, multiple first hole portions being positioned on a same location of the sheath and spaced from each other in a circumferential direction of the sheath, and multiple second hole portions being positioned on a same location of the sheath and spaced from each other in a circumferential direction of the sheath, and the engagement portion has a tapered portion which is formed in a tapered shape such that a diameter thereof gradually narrows to a distal end portion thereof, slots in which the respective projection portions are capable of being protruded are formed with the tapered portion, and an outer diameter of the tapered portion, which includes at least a part of the slots, at a distal end side thereof is smaller than an outer diameter of the projection portions when the projection portions are maximally protruded from the sheath.