An ion processing device includes, on the side of an anion exchange layer of a bipolar membrane which is formed by stacking an anion exchange layer and a cation exchange layer, an anion-side channel which is filled with an anion exchanger, and an anion removal channel provided via an anion exchange membrane, and also includes an anode for moving anions from the anion-side channel to the anion removal channel through the anion exchange membrane. Further, a cation-side channel which is filled with a cation exchanger and a cation removal channel provided via a cation exchange membrane are included on the side of the cation exchange layer of the bipolar membrane as well as a cathode for moving cations from the cation-side channel to the cation removal channel through the cation exchange membrane.