PROBLEM TO BE SOLVED: To provide a functional fiber and a related textile product, having the function of making aquatic organisms adhered thereto easy to come off during use without affecting the natural environment, and capable of diminishing their eventual waste levels. SOLUTION: This functional fiber is such one that its surface is coated with a biodegradable resin and/or water-soluble resin which has the function of making aquatic organisms adhered thereto easy to come off as a result of biodegradation and/or dissolving in water. The textile product is obtained by using the functional fibers or by coating part or the whole of a textile product comprising synthetic fibers with the biodegradable resin and/or the water-soluble resin. The textile product thus obtained also has a function similar to that mentioned above. COPYRIGHT: (C)2003,JPO