JOINT STRUCTURE

PROBLEM TO BE SOLVED: To very easily couple component members such as segments together without requiring complicated works. SOLUTION: A metal joint 1 consists of a male metal joint 2 including a coupling rod 11 having a constriction portion 15 which is smaller in diameter than a taper portion 14 at the front end thereof, and a female metal joint 3 including a female joint main body 21 for engaging with the inserted coupling rod 11. In a housing 23 of the female metal joint 3, an engaging member 25 is arranged such that both ends of a single wire with elasticity are inwardly bent to form a retaining portion 30. A fitting concave portion 31 is formed in the retaining portion 30 in a manner being concave and having almost the same diameter as the constriction portion 15 of the coupling rod 11. When the coupling rod 11 is inserted into the female joint main body 21, the retaining portion 30 engages with the constriction portion 15 of the coupling rod 11, and therefore the fitting concave portion 31 engages with the constriction portion 15, to thereby couple segments S together.