A capacitive deionization apparatus, wherein a spacing distance between electrodes of cells is uniformly maintained and a flow in the cells is optimized to improve efficiency of the deionization apparatus and contact resistance between a carbon material and a collector is reduce to improve electrical conductivity, is disclosed. The capacitive deionization apparatus which includes a plurality of electrode modules, each having a collector and electrodes disposed on upper and lower surfaces of the collector to electrically and chemically remove ions from liquid, includes a plurality of plates made of a stiff material are alternately stacked with the electrode modules such that the electrode modules are spaced at specific intervals, wherein the collector and the electrodes are pressed by a pair of adjacent plates among the plurality of plates to maintain a contact therebetween.