BaFe12O19particles were prepared by chemical precipitation and ordinary powder metallurgy methods. These particles were oriented in paraffin wax and the angular variation of coercive force was measured. By using the modified equation of Buessemet al., its variation was analyzed. It was found that reverse‐domain nucleation greatly influences the intrinsic coercive force of BaFe12O19particles; even stress‐free chemically precipitated single‐domain particles were influenced. Annealing the ball milled powder raised the coercive force drastically. This is due to the reduction of defect‐nucleation centers. It should be noted that by the chemical precipitation method a coercive force of 6000 Oe was obtained, which is one of the highest reported up to this time for isotropic BaFe12O19.