PURPOSE: To enhance the adsorptive properties of iron ion contained in an aqueous solution of an inorganic salt by bringing the solution into contact with a chelate resin having a functional group shown by a specific formula.

CONSTITUTION: An aqueous solution of a strongly acidic inorganic salt containing iron ion is brought into contact with a chelate resin with a functional group shown as -CO-NR {(CH2)pNR}-q-(CH2)r-PO3Ms wherein R is hydrogen or -CH2) r-PO3Ms; M is hydrogen, alkali metal or alkali earth metal; p is 2 to 6; q is 1 to 6; r is 1 or 2; and s is 1 or 2 depending on the valency of M. Thus iron ion contained in the aqueous solution of inorganic salt is adsorbed onto the chelate resin and removed from the solution.