To easily manufacture connecting hardware through caulking or the like dispensing with welding, having high rust-proofing performance.

A first flange 4, a second flange 5 and a folding margin 5a are formed integrally with a partial cylinder 1. Recesses 7 and 9 are formed in the partial cylinder 1 and a threaded cylinder compartment 12 is provided between the recesses. The threaded cylinder compartment 12 is formed with a locking projection 11. A connecting hole 14 is bored in parallel with the first flange 4 and a connecting cylinder portion 15 is formed on the second flange 5 to form a connecting hardware piece 17(c). Two of the connecting hardware pieces 17 are opposed together and a threaded cylinder 20 is enclosed in the threaded cylinder compartment 12(a, b) to make the connecting hardware pieces 17 overlie each other. The connecting cylinder portion 15 of the second flange 5 of one of the connecting hardware pieces which is fitted into the connecting hole 14 in the first flange 4 of the other of the connecting hardware pieces is caulked outwards to join the two connecting hardware pieces 17 together, with the folding margin 5a folded and laid on top of the first flange 4 to form the connecting hardware 23. A floor post can be constructed when the threaded rod of supporting hardware is threaded into the threaded cylinder 20.