Abstract: An ultrasonic vibration application tool equipped with a Langevin type ultrasonic vibrator which is suitably employable for ultrasonic processing devices and which efficiently generates ultrasonic vibration includes: a cylindrical housing having a contact face on a lower or bottom part of an inner surface thereof, and a lower screw part of an outer surface thereof; a bolted Langevin type ultrasonic vibrator comprising a front mass, a rear mass and a polarized piezoelectric element arranged between both masses, in which the front mass comprises a cylindrical tool-holder and a disc-shaped bulging part provided with a contact face for fitting to the contact face of the housing; and a ring-shaped counterweight having an upper screw part on an inner peripheral surface which is screwed with the screw part of the housing.