Abstract: The crystal element includes: a vibration part including a first face and a second face; a flat plate part including a first face and a second face, which has a thickness thicker than a thickness of the vibration part and is disposed in an outer edge of the vibration part on a plan view; a fixing part including a first face and a second face, which has a thickness thicker than the thickness of the flat plate part and is disposed in an outer edge of the flat plate part on a plan view; an excitation electrode disposed on the first face and the second face of the vibration part; a mounting electrode disposed at least on one of the first face and the second face of the fixing part; and a wiring electrode that electrically connects the excitation electrode and the mounting electrode.

Abstract: A flexural-mode tuning-fork type quartz crystal resonator includes a proximal portion, a pair of vibrating arm portions, and a plurality of first concave portions. The vibrating arm portions project in a direction from the proximal portion. The first concave portions are formed into groove shapes in the upper and lower principal surfaces of the proximal portion, and extend in the widthwise direction perpendicular to the longitudinal direction of the pair of vibrating arm portions. The first concave portions formed in the upper principal surface of the proximal portion and those formed in the lower principal surface of the proximal portion are arranged at a predetermined interval not to face each other.

Abstract: A flexural-mode tuning-fork type quartz crystal resonator includes a proximal portion, a pair of vibrating arm portions, and a plurality of first concave portions. The vibrating arm portions project in a direction from the proximal portion. The first concave portions are formed into groove shapes in the upper and lower principal surfaces of the proximal portion, and extend in the widthwise direction perpendicular to the longitudinal direction of the pair of vibrating arm portions. The first concave portions formed in the upper principal surface of the proximal portion and those formed in the lower principal surface of the proximal portion are arranged at a predetermined interval not to face each other.