A treatment tool (12) has a first treatment section (32) and a second treatment section (34). The first treatment section (32) has a first member (42) and a second member (44). By moving the first member (42) and/or the second member (44) along a longitudinal axis (L) of a sheath (22), it is possible to change the spacing between a first contact surface (52) of the first member (42) and a second contact surface (62) of the second member (44). When the first contact surface (52) is in close proximity to the second contact surface (62), the distal end of the rod-like second treatment section (34) is positioned farther on the distal-end side than the distal end of the first treatment section (32) is. In this state, by applying a high-frequency current to biological tissue via the second treatment section (34), the biological tissue in contact with the second treatment section (34) is incised or separated (monopolar treatment). By applying a blood vessel is placed between the first contact surface (52) and the second contact surface (62), a high-frequency current is applied to the blood vessel via the first member (42) and the second member (44), the blood vessel is coagulated and sealed (bipolar treatment). In this way, it is possible to perform both types of treatment without having to exchange the treatment tool.L'invention concerne un outil de traitement (12) qui a une première section de traitement (32) et une seconde section de traitement (34). La première section de traitement (32) comprend un premier élément (42) et un second élément (44). En déplaçant le premier élément (42) et/ou le second élément (44) le long d'un axe longitudinal (L) d'une gaine (22), il est possible de changer l'espacement entre une première surface de contact (52) du premier élément (42) et une seconde surface de contact (62) du second élément (44). Lorsque la première surface de contact (52) se trouve à proximité étroite de la seconde surface de contact (62), l'extrémité distale de la sec
