PURPOSE: To enhance the air-tightness in a throughhole by connecting a conductor provided in an inner face of a throughhole of a cover to an external electrode and supplying solder in the throughhole of the cover.

CONSTITUTION: A throughhole 17 made to a cover 3 is formed to be conical in which the diameter of the throughhole toward a vibrator 1 is smaller and a conductor 18 in the throughhole 17 made to the cover 3 is connected to each of external electrodes 4, 5. The upper part of the conductor 18 seals a smaller diametrical part of the upper part of the throughhole 17. Furthermore, the lower part of the conductor 18 is spread toward an open ridge of the throughhole 17 at a face of the cover 3 opposite to the vibrator 1. In this state, molten solder is flowed into the throughhole 17 to cover the conductor 18 covering the upper small diametrical part of the throughhole 17 and solidified into solder 22. Since the outer face side of the throughhole 17 is covered by the solder 22 in addition to the conductor 18, the air-tightness is enhanced.