A piezoelectric substrate comprising: (i) a first piezoelectric body having an elongated shape and helically wound in one direction, wherein the piezoelectric substrate does not comprise a core material; or (ii) a non-electrically conductive core material having an elongated shape; and a first piezoelectric body having an elongated shape and helically wound in one direction around the core material, wherein the first piezoelectric body comprises a helical chiral polymer (A) having optical activity, wherein a length direction of the first piezoelectric body is substantially parallel to a main direction of orientation of the helical chiral polymer (A) included in the first piezoelectric body, wherein "substantially parallel" means that the angle formed between two line segments is 0° or more but less than 30°, wherein the first piezoelectric body has a degree of orientation F, as measured by X-ray diffraction according to the following Equation (a), within a range of 0.5 or more but less than 1.0: degree of orientation F = 180 ° − α /180 ° wherein α represents a half-value width of a peak of the orientation, and wherein the first piezoelectric body is in a fibrous form composed of a single bundle or a plurality of bundles, and has a major axis diameter of a cross section of from 0.0001 mm to 10 mm. (i) a first piezoelectric body having an elongated shape and helically wound in one direction, wherein the piezoelectric substrate does not comprise a core material; or (ii) a non-electrically conductive core material having an elongated shape; and a first piezoelectric body having an elongated shape and helically wound in one direction around the core material, wherein the first piezoelectric body comprises a helical chiral polymer (A) having optical activity, wherein a length direction of the first piezoelectric body is substantially parallel to a main direction of orientation of the helical chiral polymer (A) included in the first piezoelectric body, wherein "substantially parallel" means that the angle formed between two line segments is 0° or more but less than 30°, wherein the first piezoelectric body has a degree of orientation F, as measured by X-ray diffraction according to the following Equation (a), within a range of 0.5 or more but less than 1.0: degree of orientation F = 180 ° − α /180 ° wherein α represents a half-value width of a peak of the orientation, and wherein the first piezoelectric body is in a fibrous form composed of a single bundle or a plurality of bundles, and has a major axis diameter of a cross section of from 0.0001 mm to 10 mm. wherein the first piezoelectric body comprises a helical chiral polymer (A) having optical activity, wherein a length direction of the first piezoelectric body is substantially parallel to a main direction of orientation of the helical chiral polymer (A) included in the first piezoelectric body, wherein "substantially parallel" means that the angle formed between two line segments is 0° or more but less than 30°, wherein the first piezoelectric body has a degree of orientation F, as measured by X-ray diffraction according to the following Equation (a), within a range of 0.5 or more but less than 1.0: degree of orientation F = 180 ° − α /180 ° wherein α represents a half-value width of a peak of the orientation, and wherein the first piezoelectric body is in a fibrous form composed of a single bundle or a plurality of bundles, and has a major axis diameter of a cross section of from 0.0001 mm to 10 mm. <EOS>