To provide a desalting method for leachate, capable of avoiding harmful influence caused by an increase in Ca2+ concentration.

In leachate treatment facilities where raw water 11 of landfill leachate flowing into a system is subjected to pretreatment in a Ca removing process 1 to remove Ca and the desalted raw water in which the Ca remains is desalted by an electrodialytic membrane type desalting device in a desalination concentration process 5, when Cl- concentration in the desalted raw water is lower than a set value and the concentration ratio of Cl-/Ca2+ is below a set value, the desalted concentrated water discharged from the desalting device is circulated to the Ca removing process 1 to be treated therein, increasing the concentration ratio of Cl-/Ca2+ in the desalted raw water up to the set value.