The present invention relates to a tool for surgical operation using ultrasonic waves, comprising: a vibrator generating ultrasonic waves； a cylindrical bar-shaped transmitting rod for transmitting the ultrasonic waves generated by the vibrator from the other end thereof connected to the vibrator to one end thereof； a cutter for cutting a surgical site using the ultrasonic waves transmitted from the transmitting rod, extended from one end of the transmitting rod, in which a part of the circular cross-sectional area thereof is flatly formed from the point corresponding to a first vibration node so as to allow gain step to start at the first vibration node, which is closest to one end of the transmitting rod； a rod cover for encompassing the transmitting rod using, as connection points, a plurality of vibration nodes formed when ultrasonic waves are transmitted through the transmitting rod； and a jaw for holding the surgical site while engaged with the cutter, is combined to one end of the rod cover in a tiltable manner, and is positioned to face the cutter.
