To execute a series of processings continuously from the coarse processing to the precision finishing.

Abrasive grains contained in a processing liquid 5 are electrostatically charged negatively, and to generate migration of the grains toward between a tool 8 and a work to be processed A, a DC voltage is impressed between a grinding wheel holder 7 and an electrode 18, where the side with the holder 7 is used as positive electrode. The processing pressure given to the work A from the tool 8 mounted on a grinding wheel spindle 12 can be controlled through controlling of the output of a cylinder 15. A voltage controller 19 is provided to control the DC voltage while an air controller 16 is to control the degree of valve opening of the cylinder 15, and at specified timings, an NC device 20 gives commands to the controllers 19 and 16 so as to apply a series of processings to the work A from the coarse processing to the precision finishing, generates transition of the processing conditions step by step, and gives a rotation to a processing vessel 3a situated inside so that the processing liquid 5 flows around between the tool 8 and work A.