A vibration transmitting member , configured to be attached to an ultrasonic transducer configured to generate ultrasonic vibration, the vibration transmitting member being configured to transmit the generated ultrasonic vibration, from a proximal side toward a distal side, and to vibrate at a resonance frequency in a predetermined frequency range, thereby creating vibration nodes and anti-nodes in the vibration transmitting member and the ultrasonic transducer , the vibration transmitting member comprising: a connection portion having a proximal end configured to be connected to a distal end of the ultrasonic transducer ; and a taper portion provided between the connection portion and a reference vibration node (N1) in a longitudinal direction of the vibration transmission member , the reference vibration node (N1) being defined as the vibration node being located most proximally among vibration nodes (Nj) occurring on the distal side with respect to the connection portion in a state in which the vibration transmitting member vibrates at the resonance frequency, the taper portion having such a cross-sectional area perpendicular to the longitudinal direction as to gradually decrease from the distal side toward the proximal side, the vibration transmitting member being characterized in that , in a state in which the vibration transmitting member vibrates at the resonance frequency: the taper portion transmits the ultrasonic vibration from the proximal side to the distal side, and the vibration anti-node (A1) being located closest to the connection portion among the vibration anti-nodes (Ai) occurs on the proximal side with respect to the connection portion and spaced apart from the connection portion . the vibration transmitting member being configured to transmit the generated ultrasonic vibration, from a proximal side toward a distal side, and to vibrate at a resonance frequency in a predetermined frequency range, thereby creating vibration nodes and anti-nodes in the vibration transmitting member and the ultrasonic transducer , the vibration transmitting member comprising: a connection portion having a proximal end configured to be connected to a distal end of the ultrasonic transducer ; and a taper portion provided between the connection portion and a reference vibration node (N1) in a longitudinal direction of the vibration transmission member , a connection portion having a proximal end configured to be connected to a distal end of the ultrasonic transducer ; and a taper portion provided between the connection portion and a reference vibration node (N1) in a longitudinal direction of the vibration transmission member , the reference vibration node (N1) being defined as the vibration node being located most proximally among vibration nodes (Nj) occurring on the distal side with respect to the connection portion in a state in which the vibration transmitting member vibrates at the resonance frequency, the taper portion having such a cross-sectional area perpendicular to the longitudinal direction as to gradually decrease from the distal side toward the proximal side, the vibration transmitting member being characterized in that , in a state in which the vibration transmitting member vibrates at the resonance frequency: the taper portion transmits the ultrasonic vibration from the proximal side to the distal side, and the vibration anti-node (A1) being located closest to the connection portion among the vibration anti-nodes (Ai) occurs on the proximal side with respect to the connection portion and spaced apart from the connection portion . <EOS>