A first interlayer insulation film is formed, on which a SiO₂ cap film is then formed, and degassing of moisture in the first interlayer insulation film and the SiO₂ cap film is preformed by heat treatment. Then, an Al₂O₃ film is formed on the SiO₂ cap film. Subsequently, heat treatment is performed on the Al₂O₃ in an oxidation atmosphere, thereby accelerating oxidation of its surface. Thereafter, on the Al₂O₃ film, a platinum film, a PLZT film, and an IrO₂ film are formed and patterned, thereby forming a ferroelectric capacitor including an upper electrode, a capacity insulation film, and a lower electrode.