PURPOSE: To obtain a simple removing method for fluorine ion capable of reutilizing an electrolytic solution without dumping, free from the loss of zinc, without increasing the burden of waste water treatment and even not to select a raw ore by adding titanyl sulfate dehydrate into the zinc electrolytic solution increased in fluorine ion content to adsorb to remove the fluorine ion into the produced hydrolysis product.

CONSTITUTION: Fluorine ion in the electrolytic solution is adsorbed to remove by adding titanyl sulfate dehydrate into the zinc electrolytic solution and adjusting the pH preferably to 2.1-4.2 by adding an alkali pH adjusting agent to form the hydrolysis product.