Vacuum pump

A vacuum pump, in particular a turbomolecular pump, comprises a rotor shaft 16 rotatably supported in a housing 10 by at least one radial bearing 18, 20 and an axial / thrust bearing 44. The axial bearing comprises a yoke 106 connected to the rotor shaft and a first magnetic element 108 connected to the housing and arranged axially next to the yoke to generate a magnetic force to control the axial position of the rotor shaft. The first magnetic element is separated into at least two parts (108A, 108B, figure 3) along a circumferential direction. The first magnetic element may be connected to an electromagnet to create the magnetic force. A second magnetic element 109 may be magnetically connected to the first magnetic element and arranged on the opposite side of the yoke, and may be built as one piece. A method of assembling the vacuum pump comprises providing a rotor including the rotor shaft and at least one pump element, connecting the yoke to the rotor shaft, assembling the first magnetic element around the rotor shaft, inserting the rotor and the first magnetic element into the housing, and connecting the first magnetic element to the housing.