To provide a driving method for a regenerative rotor disc.

A regenerative rotor disc 10 is provided with a plurality of radial vanes 12 on the outer peripheral part of a disc in a fluid passage, and a plurality of permanent magnets embedded in the disc with a circular locus are provided around a shaft 15, and the magnets are sealed in relation to pumped fluid. At least a pair of motor windings are put in at least one wall of a housing 20 axially adjacent to the permanent magnets in the regenerative rotor disc and sealed in relation to pumped fluid. A means is provided, for controlling the flow of electricity passing through the motor windings in order to rotatably drive the rotor disc. The rotor disc may be rotatably supported on the shaft by an outflow liquid lubrication bearing or a magnetic bearing.