While keeping the pressure as low as 5 mTorr, organic metal source gases of Pb, Zr, and Ti and an oxidizing gas such as N2O are supplied to the substrate kept at 445??? C. Since the PbTiO3 crystal nucleus is already present on the substrate, a PZT crystal grows even at the temperature as low as 445??? C. to form a PZT thin film of perovskite crystal on the substrate.