A vibration transmitting member transmits ultrasonic vibration generated by an ultrasonic transducer from a proximal side toward a distal side. The vibration transmitting member includes a connection portion connected to the ultrasonic transducer. When a reference vibration node, which is located most proximally among vibration nodes occurring on the distal side relative to the connection portion, is defined, while the vibration transmitting member vibrates at a resonance frequency in a predetermined frequency range, a taper portion is provided between the connection portion and the reference vibration node in a longitudinal direction. In the taper portion, a cross-sectional area perpendicular to a longitudinal direction gradually decreases from the distal side toward the proximal side.
