| CPC H10N 30/872 (2023.02) [H03H 9/19 (2013.01); H10N 30/085 (2023.02); H10N 30/853 (2023.02)] | 19 Claims |

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1. A piezoelectric vibration element, comprising:
a piezoelectric piece including a main surface;
an excitation electrode disposed on the main surface of the piezoelectric piece; and
a connection electrode disposed on the main surface of the piezoelectric piece and electrically connected to the excitation electrode,
wherein the piezoelectric piece has a through-hole in an area between the excitation electrode and the connection electrode in a plan view of the main surface of the piezoelectric piece,
wherein an internal wall of the through-hole located closer to the excitation electrode has at least four slopes; and
wherein a thickness of the piezoelectric piece at a portion where the excitation electrode is disposed is larger than a thickness of the piezoelectric piece in an area that includes the through-hole and is between the excitation electrode and the connection electrode.
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