PURPOSE: To obtain a synthetic fiber having antibacterial property and deodorizing activity as well as water-absorptivity and safe to human body by applying a chitosan salt to a polyester or polyamide synthetic fiber graft-polymerized with an alkali metal acrylate and/or methacrylate.

CONSTITUTION: A polyester or polyamide synthetic fiber cloth is graft- polymerized with acrylic acid and/or methacrylic acid at a polymerization ratio of 1-20%, preferably 2-10%. The graft-polymerized cloth is treated in an aqueous solution of anhydrous sodium carbonate to substitute the terminal acidic group of the acrylic acid and/or methacrylic acid with an alkali metal. The cloth is padded in an aqueous solution of a chitosan salt, squeezed and dried to obtain the objective water-absorbing antibacterial fiber holding 0.1-2.0wt.% of the chitosan salt in terms of chitosan based on the fiber.