An electrovector effect of the polarized hydroxyapatite (HA) on crystal growth in a simulated body fluid was clarified to discuss the role of the polarization energy in the effect. The polarization of the HA carried out in high dc field at 300-600°C was confirmed by thermally stimulated depolarization current measurements. The dependence of the thickness of the crystal grown layer on the induced charge was remarkably indicated in the modification of the growth rates. The growth rate under an optimum polarization condition was estimated to be almost 3 times of that by the biomimetic method. At the early stage of the crystal growth, the grown crystals were spherical and their sizes were dependent on the field strength and time for polarization. The polarization is therefore considered to effect the nucleation as well as the crystal growth.