PURPOSE: To prevent tortion from occurring when a flexible shaft is rotated around an axis in a flexible tube and to accurately transmit torque to an ultrasonic vibrator by inserting a part between a treating tool insertion channel and a driving unit in an ultrasonic wave probe through a tortion preventing member, and holding the part in a straight state as far as possible.

CONSTITUTION: A coil sleeve 30 as the tortion preventing member is formed by winding a metallic wire rod in coil shape, and its one terminal is fixed on a connector 20, and it is wound around the outer peripheral plane of the flexible tube which comprises the ultrasonic wave probe 11 spirally, and it is extended to a part located at the outside of the treating tool insertion channel 9 of an endoscope 1 and where the operation of the endoscope 1 is not disturbed in a state of holding a main body operating part 2 by an operator, etc., and the tip of the sleeve is set in a free state.