When amorphous BaTiO3 thin film is heat-treated, the resultant angle of diffraction is about 0.4° (2θ) lower than the position for ceramic BaTiO3. The low value of the angle of diffraction is considered to be due to the presence of the platinum substrate. A diffraction line for BaWO4 has also been observed. These crystals are originally compounds of tungsten and barium with uniform distributions which have been subsequently heat-treated. The BaWO4 crystals gather in narrow bands when the heat-treatment temperature is higher than 1000°C. At 1400°C, the narrow bands divide into grains with diameters greater than 10 µm, and 85% of the surface areas are composed of BaTiO3 crystal with an impurity content of less than 3W%. The dielectric constant is therefore found to increase in value.