Abstract: This filter comprises: a dielectric substrate; a plurality of resonators that are formed inside the dielectric substrate, and for which the periphery is surrounded by a shielding conductor; and input/output terminals that are formed at a portion at which the shielding conductor is not formed. The resonator closest to the input/output terminal of the plurality of resonators and the resonator that is closest to the input/output terminal of the plurality of resonators are in a point-symmetrical positional relationship.

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.