PROBLEM TO BE SOLVED: To easily and inexpensively manufacture a pipe member for a marine structure merely by containing a metal tube in a resin tube sealed at both ends, and to prevent a failure such as a breakage caused by a difference between a linear expansion coefficient of the resin tube and a linear expansion coefficient of the metal tube by loosely holding the metal tube in the resin tube.SOLUTION: The pipe member 10 for the marine structure is used as, for example, a component of a culturing raft 100, and equipped with the resin tube 18 made of a soft synthetic resin. Both ends of the resin tube 18 are sealed, in which the metal tube 20 is loosely contained. That is, an inner circumferential surface of the resin tube 18 and an outer peripheral surface of the metal tube 20 are not adhered to each other, and a dimension of the metal tube 20 is set to a predetermined value which will not exceed a dimension of the resin tube 18 within a range in which the resin tube 18 can be reinforced by the metal tube 20 against a bending or shearing force.
