To provide a grinding tool of small grinding resistance which hardly generates partial abrasion.

In the grinding tool 1, a connecting part 3 of a disk-like grinding wheel mounting plate is connected to a support plate 10 vertically fixed to a rotary shaft 8 at a lower end of the rotary shaft 8 with an unillustrated bolt. The grinding wheel mounting plate 2 has the connecting part 3 of a ring form to connect a grinding wheel holding part 4 of a ring form for holding the grinding wheel 5 with the support plate 10. A disk-like ultrasonic oscillator 7 is adhered on an upper surface of the grinding wheel mounting plate 2 at a center thereof with an epoxy resin. For instance, the connecting part 3 of the grinding wheel mounting plate is fixed to the support plate 10 with the unillustrated bolt. The grinding wheel mounting plate 2 has the grinding wheel holding part 4 of the ring form. A peripheral groove 6 is formed on the lower surface of the grinding wheel holding part 4. The grinding wheel 5 is fitted and fixed to the peripheral groove 6.