A method and a device for measuring electrical differential currents, which in addition to the alternating current component also contain a direct current component, by means of an inductive differential current transformer.The known methods for measuring mixed currents require special current transformer designs with respect to the coil winding and magnetic core material and core number. The new method copes with the same current transformers that are common for measuring pure differential alternating currents.According to the invention, the secondary coil (3) of the current transformer is controlled such that the magnetic flux (φ) linked with the secondary coil (3) inside the core remains constant, irrespective of the differential current and the secondary current (Is) required for this is measured. For this, on the one hand, the ohmic resistor (Rcu) of the secondary coil (3) is compensated in the secondary circuit (4) by an electronically produced, negative resistor (Rz), and on the other hand a defined magnetic flux is periodically restored, in that the saturation flux (φs) of the core is used as a reference point.