To provide an ultrasonic treatment instrument usable as forceps immediately after treatment by ultrasonic vibration and capable of keeping an operated part clear.

This ultrasonic treatment instrument 1 for treating organism tissue with ultrasonic vibration is provided with a ultrasound transducer 8 for generating ultrasonic vibration; a probe 4 connected at the proximal end to the ultrasound transducer 8 and transmitting the ultrasonic vibration to an ultrasonic treatment part 4a provided at the distal end; a sheath 20 for covering the probe 4; a grip member 5 arranged at the distal end of the sheath 20 to grip the organism tissue between the ultrasonic treatment part 4a and the grip member 5 when facing in an openable/closable manner with the ultrasonic treatment part 4a and operated to open/close with respect to the ultrasonic treatment part 4a; an operating means 7 for operating the grip and release of the organism tissue between the grip member 5 and the ultrasonic treatment part 4a; a grip member driving means 16 for driving the grip member 5, corresponding to the operation of the operating means 7; and an air supply means 9 for supplying air into the internal cavity of the sheath 20.