Piezoelectric resonator element and piezoelectric device

A piezoelectric device housing a piezoelectric resonator element in a package or a case, the piezoelectric resonator element comprising:

• a base portion formed of a piezoelectric material;
• a plurality of resonating arms formed integrally with the base portion and extending parallel to each other;
• a longitudinal groove formed along a longitudinal direction of each of the resonating arms;
• and
• an electrode for driving formed in the longitudinal groove, wherein:
• a width of each of the resonating arms is gradually decreased from the base portion toward a tip of the resonating arm, and a change point of width variation is provided close to the tip of the resonating arm, the width variation shifting from decrease to increase at the change point;
• and
• the change point is located closer to the tip of the resonating arm than an end of the longitudinal groove.