PURPOSE: To obtain a crystal oscillator which has reduced changes of in frequency temperature characteristics or reduced variation with time and with a small degree of vibration leakage, by setting an area of contact between a tuning fork type crystal oscillator and a supporting member within a specific range from the base terminal part.

CONSTITUTION: The width of the base part is set approximately equal to the space between the outsides of two tuning forks in their width directions. At the same time, the length is set at l0 for the base part of a tuning fork type crystal oscillator 111 which makes use of the connection of the secondary vibration of flexion and twist vibration. In this case, the area of contact between the oscillator 111 and supporting members 112/113 is set in the lengthwise direction from the base end part with an range of 0.15∼0.7l0. As a result, the displacement produced at the base part of the oscillator 111 is not transmitted to the supporting member to reduce greatly the vibration leakage. This can decrease the change in the stable frequency temperature characteristics as well as the frequency variation with time.