Patent ID: 8419269

Claim:
A portable timepiece to whose timepiece exterior assembly there is mounted a vent valve for allowing a gas pressure within it to escape to the exterior, wherein the vent valve comprises: a valve body holder fixed to the timepiece exterior assembly so as to establish communication between the interior and exterior of the timepiece exterior assembly; packing formed in a ring-like configuration of a seal material capable of elastic deformation and supported by the valve body holder; and a valve body movable between a valve-closed position and a valve-open position and equipped with a valve body shaft portion axially extending through the valve body holder while in contact with an inner peripheral portion of the packing, a valve body head provided integrally with the shaft portion, and an exhaust recess formed in the valve body shaft portion so as to be open in a peripheral surface of the shaft portion and adapted to be detached from the packing at the valve-closed position and to cross, at the valve-open position, a part of the inner peripheral portion of the packing so as to be astride this part.