It is an object of the present invention to provide an electrical
deionization apparatus having a novel constitution with excellent
deionization efficiency. As means for solving this problem, according to
one embodiment of the present invention, there is provided an electrical
deionization apparatus having deionization compartments, concentration
compartments and electrode compartments partitioned from one another by a
plurality of ion exchange membranes between a cathode and an anode,
wherein, in the deionization compartments and/or the concentration
compartments and/or the electrode compartments, at least one of anion
exchange fibrous material layers and cation exchange fibrous material
layers are disposed on one another intersecting a water-passing
direction.