The flexibly-mounted turbomolecular pump comprises a leaktight casing mounted on a structure via a mechanical damper, a vertical support driven by an electric motor, radial magnetic bearings, an axial magnetic bearing, radial detectors, an axial detector, an emergency mechanical bearing, and a control module comprising power supply circuits and servo-control circuits for the axial and radial magnetic bearings. The servo-control circuits present low stiffness and include filter circuits for defining a limited passband. The control module comprises a comparator unit for detecting abnormally large movements of the rotor from signals delivered by the axial and radial detectors, which movements are greater than predetermined thresholds. The servo-control circuits include a restabilization network and a unit for selectively activating the restabilization network during a predetermined duration after a time at which the crossing of at least one of the predetermined thresholds is detected during a movement of the rotor.