PURPOSE: To enhance the cutting property of an abrasive layer during polishing work and continuously polish an aluminum nitride material with a high polishing efficiency by using an abrasive layer of low hardness, comprising grinding powder of chrome oxide held in a low bonded state by a liquid or resin.

CONSTITUTION: An abrasive layer comprising chrome oxide powder used as grinding powder, mixed with a liquid or resin and held in a low bonded state by the surface tension or adhesion of the liquid or resin is pressed into contact with an aluminum nitride material and the abrasive layer and the aluminum nitride material are put in sliding movement relative to each other. The aluminum nitride material is thus polished with high accuracy by the abrasive layer.