Abstract: The invention relates to a method for actively balancing a rotor (1), comprising: providing a device with a rotor (1) that can be rotated around an axis of rotation and a mechanism (2) allocated to the rotor (1) for actively balancing, in which a magnetic fluid (7) is received in a fluid chamber (6) formed on the rotor (1), which partially fills the fluid chamber (6) and contains at least one of the following fluids: ferrofluid and magnetorheological fluid; holding the magnetic fluid (7) by means of a permanent magnetic field of a permanent magnet (5) arranged on the rotor (1) in an initial position in the fluid chamber (6); rotating the rotor (1) around the axis of rotation (3), and passing the fluid chamber (6) and permanent magnet (5) by an electrical exciter system with a fixedly arranged electromagnet (8) during the rotation of the rotor (1), wherein the permanent magnetic field of the permanent magnet (5) and an electromagnetic field of the electromagnet (8) here overlap in an activated state for active