To provide shaft sealing structure to prevent corrosion of the bearing for rotatably fixing a rotor to a housing due to reactive gas or adhesion of the product generated by the reactive gas in a vacuum pump having the rotor used in the process passing the reactive gas such as a manufacturing process of semiconductors.

The structure is equipped with the rotor rotatably fixed by the bearings at the ends and a casing storing the rotor. The casing is provided with a ventilation path for sending inactive gas to the bearings at the part near the bearings, the function controlling flow rate or/and pressure of the inactive gas and the function raising the temperature of the inactive gas in the vacuum pump having a suction port and a discharge port.