The present invention aims at limiting the pressure loss and smoothly discharging water treated by ion exchangers to the outside of the apparatus. Ion exchanging apparatus 1 has outer vessel 3 that has inner space 2; and ion exchanger support 4 that separates at least a part of inner space 2 into upper space 2a and lower space 2b and that can support ion exchangers to be loaded in upper space 2a. At least a part of an upper surface of the ion exchanger support is made from at least one screen which supports the ion exchangers and which has a flow path allowing water treated by the ion exchangers to flow into the lower space 2b.