Device structure 100 for iontophoresis provides electrode 101 and electrically conductive layer 102. Electrically conductive layer 102 contains active ingredient D and basic water swelling methacrylate copolymer P1 and/or acidic water swelling methacrylate copolymer P2. Electrode 101 and electrically conductive layer 102 are placed into a hollow of backing 103 and electrode terminal 104 is connected to electrode 101 through backing 103. Adhesive layer 105 is set around backing 103, and liner 106 to be removed when using the device, is placed so as to cover the hollow of backing 103.