In the present study, we clarified quantitatively the constrained effect of bracing members having shear bolted joints to the lateral buckling behavior by the results of the experiments and the non-linear analyses. And we proposed the design formula of chord members of tubular truss beams with bolted joints. This formula was derived from the modified lateral buckling conditional equation obtained by the energy method. And it was taking the constrained effect obtained by the resuluts of eigenvalue analyses into consideration. Consequently, we confirmed validity of the proposed design formula.