The crystallization process of BaFe12O19 from barium iron borate glass prepared by the twin-roller quenching method has been investigated by Fe K-edge XAFS and XRD. XRD patterns revealed that at 773 K diffused diffraction peaks appeared in addition to the glass pattern, and at 873 K BaFe12O19 was crystallized. The XANES spectra changed at 773 K and resembled that of BaFe12O19 above 823 K. The Fe-0 bond distances and coordination numbers derived from EXAFS spectra became closer to those of BaFe12O19 with increasing the heat treatment temperature. We found that the change of the local structure around Fe3+ ion began at 773 K and then Fe3+ ion crystallized to form BaFe12O19 above 873 K.