A probe unit which is configured to treat a treatment target region of a biological tissue by ultrasonic vibration, includes : a probe including a vibration transmitting section through which the ultrasonic vibration is transmitted from a proximal end side toward a distal end side, a treatment section that is arranged on the distal end side of the vibration transmitting section and configured to treat the treatment target region by the ultrasonic vibration transmitted through the vibration transmitting section, and a surface section provided on the treatment section； and a protruding marking section that protrudes from the surface section of the probe and is configured to mark and define the treatment target region with the treatment section which is configured to treat the biological tissue using the ultrasonic vibration transmitted to the treatment section.
