Abstract: A chelate-forming filter which comprises a filter medium made of natural, regenerated, or synthetic fibers wherein the fiber molecules have, incorporated therein, chelate-forming functional groups represented by general formula (1) [wherein G represents a residue of a chain sugar alcohol or of a polyhydric alcohol; and R represents hydrogen, (lower) alkyl, or -G (wherein G has the same meaning as the above G, and the two G's may be the same or different)] or (3) (wherein R1, R2, and R3 each represents lower alkylene; and n is an integer of 1 to 4).