PROBLEM TO BE SOLVED: To provide a hollow circular pipe capable of satisfying weight saving and multifunctionality, and a manufacturing device of the hollow circular pipe, and a manufacturing method of the hollow circular pipe.SOLUTION: A hollow circular pipe 100 of this invention includes an outer layer 220 having an inclination structure where porosity is different in a thickness direction, an inner layer 210, and a coating layer 230. In the inclination structure of the hollow circular pipe 100, the porosity is made lower on a far side to the axial core of the outer layer 220 than on a close side. Consequently, the hollow pipe 100 has multifunctionality having at least a light-weight property and a mechanical physical property.SELECTED DRAWING: Figure 1

You do not currently have access to this content.