PURPOSE: To simply enhance the deteriorated magnetic characteristics by finely pulverizing a hard oxide-base magnetic material by a mechanically pulverizing means and by heat-treating the resulting powder at a specified temp. in the air.

CONSTITUTION: Barium carbonate is mixed with iron oxide in a suitable ratio, and the mixture is calcined at about 1,200W1,300°C to form barium ferrite. This barium ferrite is finely pulverized by a mechanical means using a vibrating mill, a ball mill or the like, and by removing coarse particles and fine particles having below a particle size corresponding to single magnetic domain structure by sieving or classification, particles having a particle size almost corresponding to single magnetic domain structure are obtd. The resulting hard oxide-base magnetic powder is heat treated at ≤800°C in the air with an electric furnace or the like. Thus, the internal strain of the crystal lattice and lattice asymmetry produced in the particles by a mechanochemical reaction in the pulverizing stage can be eliminated, and the magnetic characteristics can be restored.