PURPOSE: To joint truss structures reliably by holding the mounting attitude of a spherical node, i.e. a spherical work, through at least two pin holes made through a referential machining face separated from a referential machining threaded hole.

CONSTITUTION: A referential machining threaded hole 5 for fixing a work to a work fixing table 2 is made through the referential machining face 10 of a spherical node, i.e. a spherical work 1, and at least two pin holes 11, 12 are formed at separated positions. Then fixing pins 13, 14 of the work fixing table 2 are engaged with the pin holes 11, 12 and the spherical work 1 is secured with a fixing bolt 4, while a jointing face 15 and a screw hole are formed by means of a tool 9 without accompanying rotation. When a machined spherical node 17 is machined again, the pins 13, 14 are engaged again with the pin hole 11, 12 thus reproducing the machining attitude. Consequently, accurate machining can be made efficiently and truss structures can be jointed reliably through spherical nodes.