Ion exchange fibers with quaternary ammonium groups, phosphonium groups, or thiol groups etc., were prepared by graft, copolymerization of vinyl monomers on loofah fiber which is one of the natural fibers. Methacryloyloxyethyl trimethyl ammonium chloride (METAC), tributyl-4-vinylbenzyl phosphonium chloride (TRVB), and epithiopropyl methacrylate (ETMA) were used as vinyl monomers. Graft copolymerization of METAC on loofah could be carried out in water using ammonium cerium (IV) nitrate. Graft copolymerization of TRVB and ETMA on loofah could be performed in water and water-dimethylsulfoxide mixed solution using hydrogen peroxide as an initiator, respectively. The optimum conditions for each graft. copolymerization were investigated in detail. Ion exchange fibers (LE-TTA) having both thiol groups and triethylenetetramine side chains were obtained by treatment of L-g-ETMA (LE) with triethylenetetramine. LE and LE-TTA had high adsorption ability for silver ions. LE-TTA-Ag exhibited high antibacterial activity against E. Eoli and S. aureus, but LE-Ag did not. On the other hand, L-g-METAC and L-g-TRVB also exhibited high antibacterial activity against E. Eoli and S. aureus.