To provide a method for joining skeleton cylindrical bodies to each other and fitting an object to the skeleton cylindrical body.

An interposing member 4, having at least two bored plates 41 is used, a recess part 43 is provide inside the skeleton cylindrical body 2 near its end part, and after the diameter of the end part of the skeleton cylindrical body has contracted, it is returned to its original dimension, and the recessed part 43 and the inside of the bored plate 41 of the interposing member are engaged with each other. Preferably, a part of the ring of the skeleton cylindrical body is cut, so as to facilitate expansion/contraction of the diameter of the ring before the diameter of the end part of the skeleton cylindrical body 2 is contracted or returned to its original dimension.