Abstract: A joint device enables to join a brace member, into which regulated pretension is exactly introduced, to unmovable connector nodes, comprising a steel rod 1 having a swelled portion 1A and a threaded connector portion 1B formed on the end thereof, respectively, one sleeve 3 providing an external threaded part 3A joined to one node 2M, which contacts a swelled portion 1A: and another sleeve 4 providing an external threaded part 4A joined to node 2N, which engages threaded connector portion 1B. The length from a node-contact face 3c of sleeve 3 to a node-contact face 4c of sleeve 4 is selected equal to difference of length between both nodes 2, 2 from length for generating a preferable elongation enough to introduce regulated pretension into steel rod 1.