PURPOSE: To obtain a piezoelectric element with superior piezoelectric transducing efficiency by using reduced strontium titanate single crystal for a substrate, forming a thin film consisting principally of lead titanate thereupon, and providing an electrode on the thin film.

CONSTITUTION: The thin film 12 of lead titanate single crystal is formed by epitaxial growth on a polished specular surface of the substrate 11 of reduced strontium titanate single crystal on RF magnetron sputtering basis. Chromium and gold are vapor-deposited as an upper electrode on said thin film 12 and polarized to form a single domain, and lead wires 14 are provided to the upper electrode 13 and substrate 11. Consequently, the thin film of lead titanate formed by epitaxial growth is used as it is, the piezoelectric conversion effect is superior as compared with the use of ceramics of lead titanate, and this element is extremely useful for an ultrasonic generator, ultrasonic detector, etc.