The treatment tool capable of grasping a living tissue has a rotating member that is supported by the first clamping member and is rotatable in the first direction and the opposite direction. The rotating member has a distal end adjacent to the distal end portion of the first clamping member and a proximal end adjacent to the proximal end portion of the first clamping member, and the rotational axis includes a central position between the distal end and the proximal end. It is supported on the side close to the tip. The first gripping surface is provided on the side of the rotating member that is close to the second clamping member, and grips the living tissue. The second gripping surface is provided on the side of the second clamping member that is close to the rotating member, and faces the first gripping surface and cooperates with the first gripping surface of the rotating member to grip the living tissue.生体組織を把持可能な処置具は、第１挟持部材に支持され、第１方向及びその反対方向に回動可能な回動部材を有する。回動部材は、第１挟持部材の先端部に近接する先端及び第１挟持部材の基端部に近接する基端を有し回動軸が先端と基端との間での中央位置を含む先端に近接する側に支持されている。第１把持面は回動部材のうち第２挟持部材に近接する側に設けられ、生体組織を把持する。第２把持面は第２挟持部材のうち回動部材に近接する側に設けられ、第１把持面に対向し回動部材の第１把持面と協働して生体組織を把持する。
