A medical treatment tool (1) is provided with a long flexible section (2). A wire (5) passes through the flexible section (2) along the longitudinal axis. To a leading end of the flexible section (2), a pair of jaws (10a, 10b) are mounted via a movable member (3). When a basal end of the wire (5) is pulled, the leading end of the wire (5) pulls a pin (12) and the pin (12) closes the pair of jaws (10a, 10b) so that the jaws (10a, 10b) hold a tissue (P). When the flexible section (2) is curved, a part of the wire (5) comes into close contact with an inner wall (2b) of the flexible section (2). Thus, the wire (5) is fixed to the flexible section (2) by friction at the aforesaid part. Therefore, the force of the leading end of the wire (5) for pulling the pin (12) is smaller than the force for pulling the basal end of the wire (5). Consequently, the power of the jaws (10a, 10b) for holding the tissue (P) is small. When the flexible section (2) is pulled toward the basal end side in this state, a tension applied to the wire (5) increases between the leading end of the wire (5) and the part where the wire (5) closely contacts with the inner wall (2b). As a result, the force of the jaws (10a, 10b) for holding the tissue (P) increases.Linvention concerne un outil de traitement médical (1) qui comprend une section souple longue (2). Un fil (5) passe à travers la section souple (2) le long de laxe longitudinal. À une extrémité avant de la section souple (2), une paire de mâchoires (10a, 10b) sont montées par lintermédiaire dun élément mobile (3). Lorsquune extrémité de base du fil (5) est tirée, lextrémité avant du fil (5) tire une broche (12) et la broche (12) ferme la paire de mâchoires (10a, 10b) de telle sorte que les mâchoires (10a, 10b) maintiennent un tissu (P). Lorsque la section souple (2) est incurvée, une partie du fil (5) entre en contact étroit avec une paroi interne (2b) de la section souple (2). Ainsi, le fil (5) est fixé à la section souple (2) par frottement
