To suppress unstabilization of the grinding rate associated with deterioration of the conditioning ability by pressurizing the liquid to be sprayed on a grinding cloth, removing grinding chips clogged in the surface, and sharpening the surface to regenerate the ruggedness of the surface and to protect a substrate.

A liquid inlet 1c to take in the pressurized liquid into an inside flow passage 1b is connected to a nozzle body 1a, branch flow passages 1d are branched from the flow passage 1b, and nozzles 1, 1... are respectively connected to each branch flow passages 1d. When grinding of the substrate surface is completed by the grinding cloth of a grinding table, the nozzle body 1a is lowered, and the pressurized liquid is sprayed from high pressure water spray nozzles 1, 1... toward the grinding cloth of the grinding table. Grinding chips clogged in the surface of the grinding cloth are floated on the surface by the liquid pressure, and removed by the water flow. Raising of the surface of the grinding cloth is promoted by the liquid pressure from the high pressure water spray nozzle 1, and sharpening is performed to regenerate the ruggedness on the surface.