A probe is connected to an ultrasonic transducer configured to generate ultrasonic vibration. The probe includes an elongated main body portion, and a cylindrical engagement portion. The main body portion includes is configured to transmit the ultrasonic vibration. The ultrasonic vibration is input to the engagement portion. The engagement portion includes: a connection portion that is connected to the ultrasonic transducer, and a holding cylindrical portion that is continuous to the connection portion, and that holds the proximal end portion of the main body portion.
