A resonator element includes a base portion and a pair of vibrating arms that are provided integrally with the base portion, are aligned in an X-axis direction, and extend in a Y-axis direction from the base portion. Each of the vibrating arms includes an arm portion and a wide hammerhead that is located on the free end side of the arm portion and has a greater length in the X-axis direction than the arm portion. Assuming that the length of the vibrating arm in the Y-axis direction is L and the length of the hammerhead in the Y-axis direction is H, the relationship of 1.2%
