PURPOSE: To obtain a uniform and accurate polished surface with its smoothness improve by adding mixing friction-crushing force and/or mechanical impact force to the surface of powder to solidify powder whose hardness is higher than the former.

CONSTITUTION: Powder whose hardness higher than powder to be worked is partly driven into the powder to be worked by mixing friction-crushing force and/or mechanical impact force. Following the above, a surface of a compound abrasive material is formed by the powder whose hardness higher than the powder to be worked.