An ultrasonic treatment device includes a vibration transmitting section which includes an amplitude enlarging section provided to a distal direction side of an ultrasonic vibrator and configured to enlarge an amplitude of an ultrasonic vibration, and an ultrasonic probe extended to the distal direction side of the amplitude enlarging section along a longitudinal axis, and which is configured to transmit the ultrasonic vibration to a distal end of the ultrasonic probe, and a hole defining portion which is extended toward a proximal direction along the longitudinal axis from a distal end portion of the vibration transmitting section, and which defines a hole-shaped portion inside the vibration transmitting section. The ultrasonic treatment device includes a tube member which is inserted into an inside of the vibration transmitting section from an outside of the vibration transmitting section, a tube distal end of the tube member being connected to the hole defining portion of the vibration transmitting section at a node position of the ultrasonic vibration to the distal direction side of the amplitude enlarging section.
