Patent ID: 8294337

Claim:
A flexural vibration piece, comprising: a base portion; and a vibrating arm portion that extends in a first direction from the base portion and that flexurally vibrates, wherein the vibrating arm portion includes: a first main surface and a second main surface opposite to each other; a first groove portion formed in the first direction in the first main surface; and a second groove portion formed in the first direction in the second main surface, and wherein the first groove portion and second groove portion are positioned side by side in a second direction perpendicular to the first direction in plan view from a normal direction of the first main surface, each of a first depth of the first groove portion and a second depth of the second groove portion are smaller than a thickness of the vibrating arm in the normal direction between the first main surface and second main surface, and the sum of the first depth and second depth is greater than the thickness, and a mass portion is provided on at least one of the first main surface and the second main surface.