To provide a method and a device for adjusting a grounding surface which can prevent generation of powder dust at the time of performing grounding adjustment and can solve problems of a conventional grounding surface adjustment and powder dust prevention method at low costs.

Water and air are merged into a flow of polishing and cleaning materials in spray nozzles 1, 2, and 3 by simultaneously sucking the water and air from inlets or halfway intake ports 4 of spray nozzles 1, 2, and 3 for polishing and cleaning materials. By this way, the water and the polishing and cleaning materials are effectively mixed and the polishing and cleaning materials in the spray nozzles 1, 2, and 3 are kept at a uniformly wet state, so that adjustment of grounding surface can be carried out by spraying the polishing and cleaning materials while restraining generation of powder dust.