An iontophoresis device may be capable of preventing or reducing the generation of gas, or the production of undesirable ions, due to an electrode reaction occurring in an electrode assembly; or the alteration of an active agent due to a chemical reaction upon energization. A doping layer made of a substance such as a conductive polymer that effects an electrochemical reaction due to the doping or de-doping of an ion, may be formed in an electrode in an active electrode assembly or counter electrode assembly of an iontophoresis device.