Ba(OH).sub.2.8H.sub.2O is fused by heating. The fused Ba(OH).sub.2 is allowed to react with TiO.sub.2 powder having a specific surface area of 250 m.sup.2/g or more to prepare a cubic crystalline BaTiO.sub.3 having high crystallinity. The BaTiO.sub.3 is calcined to yield a fine, tetragonal crystalline BaTiO.sub.3 powder having high crystallinity. Thus, a high quality BaTiO.sub.3 having high crystallinity can be prepared at a low cost.