A forceps type (scissors type) treatment instrument (7) is provided with: an ultrasonic probe (52) protruding from a treatment instrument body (20) at a position separated to the front end side from a shaft section (22) for supporting a clamp arm (21) so that the clamp arm (21) can pivot relative to the treatment instrument body (20)； a jaw (61) provided to the clamp arm (21) at a position separated to the front end side from the shaft section (22) and capable of being, in association with the pivoting operation of the clamp arm (21), displaced between a closed position at which the jaw (61) is in contact with the ultrasonic probe (52) and an open position at which the jaw (61) is separated from the ultrasonic probe (52). A stopper (70) is extended toward the clamp arm (21) side from the treatment instrument body (20) side while the front end-side edge of the stopper (70) is set closer to the front end side than the path of the base end of the jaw (61), the path being formed when a base (60) is displaced. When the jaw (61) is in an open state, the stopper (70) prevents the entry of an organism into the gap (within a region (64), the treatment of which is impossible) between the treatment instrument body (20) and the clamp arm (21) at a position between the base end of the jaw (61) and the shaft section (22).La présente invention concerne un instrument de traitement (7) de type forceps (de type ciseaux) comprenant : une sonde échographique (52) faisant saillie depuis un corps d'instrument de traitement (20) en un point séparé, en direction de l'extrémité avant, d'une partie axe (22) destinée à supporter un bras de serrage (21) de façon à ce que ledit bras de serrage (21) puisse pivoter par rapport au corps d'instrument de traitement (20) ； une mâchoire (61) équipant le bras de serrage (21) en un point séparé, en direction de l'extrémité avant, de la partie axe (22) et pouvant, en association avec le processus de pivotement du bras de serrage (21), passer d'une positi
