Abstract: [Object] To provide a timepiece spring whereby it is possible to ensure high precision and stable operation of precision mechanisms such as timepieces, and to provide a timepiece spring, a mainspring, a hairspring, and a timepiece wherein long-term operation can be ensured when the spring is used as a power source. [Means] A mainspring used as a source to power a drive source is formed from a special titanium alloy and has an S-shape when freely spread out, wherein the inflection point at which the curving direction of the freely spread-out shape changes is formed farther inward than the midpoint of an inner end at the end of the winding side and an outer end at the end opposite the inner end. The titanium alloy constituting the present invention has high tensile stress and a low average Young's modulus, making it possible to increase the mechanical energy accumulated in the mainspring 31.

Abstract: Provided is a method for manufacturing a piezoelectric element that has excellent piezoelectric characteristics and can be made into a thicker film. A piezoelectric thin film is crystallized by a process in which piezoelectric precursor films 4021 through 4025 containing the metal elements of a piezoelectric ceramic are coated with a material, dried, pyrolyzed, and then heat-treated under prescribed conditions in a diffusion furnace. With this method, a piezoelectric thin film can be made into a thicker film without initiating cracking.