An optical element satisfactory in transparency and characteristics as an optical modulation element, and a piezoelectric substance element satisfactory in precision and reproducibility as a fine element such as MEMS can be provided. The piezoelectric substance element includes, on a substrate, at least a first electrode, a piezoelectric substance film and a second electrode. The piezoelectric substance film does not contain a layer-structured boundary plane; the crystal phase constituting the piezoelectric substance film comprises at least two of a tetragonal, a rhombohedral, a pseudocubic, an orthorhombic and a monoclinic; and the piezoelectric substance film includes, in a portion in which a change in the composition is within a range of ±2%, a portion where a proportion of the different crystal phases changes gradually in a thickness direction of the film.