The ultrasonic treatment device for joint includes a bone cutting mode that vibrates at a first frequency and a first amplitude, a second frequency that is higher than the first frequency, and a first frequency that is smaller than the first amplitude. A cartilage lysis mode that vibrates at an amplitude of 2, a first vibration velocity that is a product of the first frequency and the first amplitude, the second frequency, and the second amplitude, And the second vibration speed that is the product of関節用超音波処置具は、第１の周波数および第１の振幅で振動する骨切削モードと、前記第１の周波数よりも高い周波数である第２の周波数および前記第１の振幅よりも小さい第２の振幅で振動する軟骨溶解モードと、を有し、前記第１の周波数と前記第１の振幅との積である第１の振動速度と、前記第２の周波数と前記第２の振幅との積である第２の振動速度とが一致または略一致する。
