Grooves (2a, 3a) are formed in the tines (2, 3) of an oscillator, side surface electrodes (2e, 3e) are formed on the side surfaces of the tines, and groove electrodes (2d, 3d) are formed in the grooves, respectively. The width of the tines (2, 3) is fixed through the whole length of the tines, while, in a part close to the lower end of the tine, the width of the grooves (2a, 3a) is gradually reduced toward the lower end, whereby a trapezoid region (D) is formed between the side surface of the tine and the groove in this part, and a part of the region (D) is used as an arrangement region of an electrode (5c) which connects the groove electrode and the side surface electrode.