The invention relates to a device for the cosmetic treatment of keratin materials with an electric current, comprising at least: —a power supply system (1), —a reservoir (3) containing a cosmetic composition (P), —an end piece (2) comprising an electrode (4) and at least one applicator member (6, 7), said applicator member (6, 7) delimiting an outer wall (61, 71) that is able to be filled with product contained in the reservoir (3), —a counter electrode (5), —a system for regulating the quantity of composition (P) exiting the reservoir (3) on the basis of the impedance measured between the electrode (4) and the keratin materials, the electrode (4) and the applicator member (6, 7) being designed such that the composition (P) is the only conductive substance in contact with the skin while the device is being used.