As shown in FIG. 2, when the vibrating reeds 1a, 1b of the tuning fork vibrator 1 vibrate, during one half period of the vibration the vibrating pieces 1a, 1b are moving toward each other, while during the other half period of the vibration, the vibrating pieces 1a, 1b are moving apart; as indicated by arrows S. Since the weight of parts such as the housing 2 and mounting arrangement, other than t