To provide a method for treating hydrofluoric acid waste liquid that can efficiently separate hydrofluoric acid and hexafluorosilicate using an electric deionizer.

A method for treating hydrofluoric acid waste liquid using an electric deionizer 10 provided with at least a cathode chamber and concentration chamber 5, a desalting chamber 7 and an anode chamber and concentration chamber 6 by disposing an ion exchange membrane between an anode 2 and a cathode 1, includes a hydrofluoric acid recovery process for filling the desalting chamber 7 with anion exchange resin 9, and allowing hydrofluoric acid waste liquid to pass through the desalting chamber in a state of stopping energization to the electric deionizer, to cause hydrofluoric acid-containing liquid with reduced hexafluorosilicate to flow out of the desalting chamber 7, and a regenerating process for regenerating the anion exchange resin 9 by allowing water to pass through the desalting chamber 7 and the concentration chambers 5, 6 in a state of energizing the electric deionizer 10.