To secure high machining accuracy by effectively preventing omission of abrasive grains and a binder during grinding while excellently maintaining the sharpness of a grinding wheel.

The grinding device is composed so that the surface of a workpiece can be ground by pressing the grinding wheel 16 to the workpiece rotationally driven integrally with a main spindle after rotationally driving the cup-shaped grinding wheel 16. The grinding wheel 16 is pressed to a dressing grinding wheel 26a while rotationally driving the grinding wheel 16 and a dress board 26 together after mounting the dress board 26 to the main spindle at the time of dressing the grinding wheel 16. A washing nozzle 30 and a vacuum nozzle 32 are provided in turn from the upstream side in the rotation direction of the grinding wheel 16. A grinding wheel face is washed by spraying washing waster, to which ultrasonic vibration is imparted, from the washing nozzle 30 to the grinding wheel 16 during dressing. The washing part is sucked by the vacuum nozzle 32.