To enhance the efficiency of processing in plane grinding and/or back face grinding and so on for a wafer.

Regardless of a grinding process and a lapping process, a wafer 16 is proceed by lapping while being ground by a cup type grinding wheel 28 with isolated abrasive grains supplied. When the wafer 16 is processed by the cup type grinding wheel 28, its grinding resistance is kept under surveillance, and isolated abrasive grains are applied when processing resistance is found to have exceeded a set value. And furthermore, the wafer is processed by grinding while isolated abrasive grains are applied immediately before or prior to a set time when spark-out is started, or at the time of starting spark-out, or after the specified period of time has elapsed.