A regulating device regulates the flow rate of non-ferromagnetic, electrically conducting liquids and melt streams through magnetic fields inducing eddy currents in the melt stream. In a preferred embodiment, the regulating device controls the melt stream using at least one stationary magnetic field with a constant polarity, at least one stationary magnetic alternating field or using a multi-poled magnetic travelling field, in such a way that the magnetic field lines transversally penetrate the melt flow across the entire cross section thereof and such that a voltage is induced in the melt stream by the magnetic fields.