Abstract: A probe configured to be connected to a transducer unit configured to generate ultrasonic vibration, includes an elongated vibration transmission portion configured to transmit the ultrasonic vibration; and an engagement member provided on and/or near an outer circumference at a position which becomes a node of the ultrasonic vibration when the ultrasonic vibration is transmitted to the vibration transmission portion, the engagement member being formed by a material of an identical to or smaller damping rate than a damping rate of the ultrasonic vibration in the vibration transmission portion, and the engagement member being engaged with an exterior member disposed on an outer side of the vibration transmission portion.