This invention relates to a turbomolecular vacuum pump (1) of the type having stator blades (10) which are disposed in multistage fashion within a casing (2) and in the axial direction thereof, and rotor blades (11) which are located between the respectively adjacent stator blades (10) and which are disposed on the outer periphery of a rotor (12) situated centrally of the casing (2). A motor rotor (17) is fixed to a rotating member (5) which is formed of the rotor (12) having the rotor blades (11) fixed to its outer periphery, and a motor stator (18) opposite to the motor rotor (17) is arranged to construct the drive mechanism of the rotating member (5). The rotating member (5) is supported at its lower part by a pivot type plain bearing (15). A magnetic bearing (20) is arranged in a manner to oppose between the lower end of the rotor (12) and a supporting member (6) for the rotating member (5).