An endoscopic treatment tool (10) is provided with: an adapter (11) that is attached to a distal end section of an insertion section (2) of an endoscope (3) provided with, at a distal end surface thereof, an observation optical system (4) and an opening of a channel (8)； a grip forceps (14) provided with a grip part (13) at a distal end of a flexible elongated part (12)； and a swing member (15) that is supported on the adapter so as to allow swinging, and supports, at a swinging end, the vicinity of the grip part of the grip forceps. In the state where the adapter has been attached to the distal end section of the insertion section, the elongated part is supported so as to allow movement in a longitudinal axis direction of the insertion section at a circumferential direction position on the opposite side from the opening, with the observation optical system therebetween； the swing member is arranged so as to be able to swing about an axis extending in a direction intersecting a direction of arraying of the observation optical system and the opening, and with the longitudinal axis direction； and there is provided an edge (17) that, when a tractive force has been applied to the adapter in a direction going toward the observation optical system from the opening, in relation to biological tissue gripped by the grip, applies force to the biological tissue in the direction opposite the tractive force, on the side opposite the observation optical system, with the opening therebetween.L'invention concerne un outil de traitement endoscopique (10) comprenant : un adaptateur (11) qui est fixé à une section d'extrémité distale d'une section d'insertion (2) d'un endoscope (3) pourvu, au niveau d'une surface d'extrémité distale de celui-ci, d'un système optique d'observation (4) et d'une ouverture d'un canal (8) ； une pince de préhension (14) pourvue d'une partie préhension (13) au niveau d'une extrémité distale d'une partie allongée flexible (12) ； et un élément oscillant (15) q
