<；P>；PROBLEM TO BE SOLVED: To provide a structure for improving water quality, having strong resistance to torsion and stretch in water, and preventing the damage and the breakage by running water, waves or the like. <；P>；SOLUTION: The structure for improving the water quality is obtained by attaching a weight member 22 to the lower end part of a cylindrical body 20 and a float member 24 to the upper end part of the cylindrical body 20. The cylindrical body 20 is obtained by forming a fiber outer pipe 14 by weaving a carbon fiber 14A into a lattice shape on the outer periphery of a resin inner pipe 12, and radially installing a plurality of thready fibers 16 comprising the carbon fiber in the outside of the fiber outer pipe 14. The weight member 22 is installed in the bottom part 30 in the water, and the cylindrical body 20 is swung like a seaweed in the water by the float member 24 floating on the water surface 32. The cylindrical body 20 has the strong resistance to the torsion and the stretch to prevent the damage and the breakage. Microorganisms and aquatic plants such as alga are propagated in the fiber outer pipe 14 and the thready fibers 16, and fish and shellfish inhabit by aiming them. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
