PURPOSE: To make it possible to perform grinding in a large quantity inexpensively and highly accurately, by performing flowing frictional abrasion in a vibration barrel device.

CONSTITUTION: Many alumina substrates 2, which are coarsely ground in advance, are put in a grinding chamber 1 together with prism shaped grinding stones 3, whose quantity of alumina inclusion is 902. Vibration, whose amplitude is 1.5W4mm and number of vibration is about 1,750RPM, is imparted. Under this state, the grinding stones 3 and the substrates 2 are well abraded by the rotation or spiral movement. Thus, the product having the desired surface roughness can be obtained.