Probe, treatment device, and treatment system

A probe which is configured to treat a bone by ultrasonic vibration, includes: a treatment section which is arranged on a distal end side of a vibration transmitting section, to which the ultrasonic vibration is transmitted through the vibration transmitting section. The treatment section includes: a cutting blade that includes a treatment surface, and cuts and treats the bone by the treatment surface; a protrusion that is provided at a position different from the cutting blade, protrudes in a direction different from the protruding direction of the treatment surface of the cutting blade, marks the bone, and defines a position of the bone to be treated with the cutting blade; and a regulation surface that is formed at a position where the protrusion is provided, and regulates entrance of the protrusion into the bone beyond a predetermined level.