To provide an electrode structure which prevents the generation of failure of an electrode and can be more miniaturized in the electrode structure of a tuning fork crystal.

A tuning fork crystal oscillator or a tuning fork crystal oscillator with a trench has flat electrodes on the respective fronts and rears of a left arm portion, and a right arm portion and has side surface electrodes on the respective side surfaces of the arm portions. In the oscillator, the flat electrodes of the front and the rear of the respective arm portions are electrically connected with each other by using conducting films which are arranged at fork sides in the vicinities of roots of the respective arm portions.