A surface mount piezoelectric oscillator includes a piezoelectric resonator with a container main body, a plurality of external terminals, a mounting board with an IC chip, a plurality of connecting terminals, and a solder ball. The solder ball bonds the plurality of external terminals and the plurality of connecting terminals by melting and hardening. The solder bonding portion has approximately a circular shape with approximately a same size as a size of the connecting terminal of the mounting board. The solder ball placed on the connecting terminal of the mounting board is melted, self-aligned, and hardened so as to form a solder fillet of nearly axial symmetry. The solder fillet bridges between the both electrodes and bonds the connecting terminal of the mounting board and the solder bonding portion of the external terminal of the piezoelectric resonator.