PURPOSE: To obtain an abrasive medium which well preserves its cutting ability, by dispersing a cubic boron nitride grit coated with an anti-oxidizing substance in a metal matrix.

CONSTITUTION: This abrasive medium is prepared b dispersing a cubic boron nitride grit coated with an anti-oxidizing substance in a metal matrix. Preferably, the anti-oxidizing substance has a hardness larger than 1,250 Vickers and comprises aluminum nitride. The metal matrix is preferably a nickel-based alloy. The depth of the aluminum nitride coating is preferably from 15 to 20 μm. The anti-oxidizing substance is vapor-deposited in, e.g. a fluidized bed reactor.