Piezoelectric resonator element and piezoelectric device

A piezoelectric resonator element (32) includes a base portion (51) formed of a piezoelectric material, a plurality of resonating arms (35,36) 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. 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 shifts from decrease to increase at the change point. The change point is located closer to the tip of the resonating arm than an end of the longitudinal groove.