PURPOSE: To obtain a means of preventing dust from being generated by wearing an O ring even in a condition of high temperature, relating to a vacuum seal method between a partition of a vacuum device and a shaft inserted through the partition.

CONSTITUTION: In a vacuum seal method between a partition 1 of a vacuum device and a shaft 2 inserted through the partition, a seal member 3 for burying a part between the partition 1 and the shaft 2 is provided. The seal member 3 provides a ring-shaped groove 7, for fitting an O ring 4, formed of a cylindrical film 5 between the O ring 11 and the shaft 2 and further of a side surface 6 with an opposite side to the film 5 in a narrow tapered shape to a bottom part direction. Constitution is provided such that the O ring 4 is deformed by pressing it with a retaining jig 8 to compress the film 5, and it tightens the shaft 2 to hold a vacuum of the vacuum device.