The present study presents a new FEM element for buckling analysis of members of H-section and its application to spatial structures. The element is fundamentally composed of three parallel beams together with two struts normal to the three elements, enabling a consideration of flexural-torsional buckling. The present study, first, performs static analysis of members under torsional moments. Second, the study performs buckling analysis of members subjected to axial forces, followed by lateral buckling analysis of members under bending moments at both ends. Through the comparison of the results with the solutions based on differential equations, the study validates the proposed element. Third, the study extends analyses to two structures which represent the fundamental structural characteristics of spatial structures, also considering the effect of stiffening members added to spatial structures. Finally, based on discussions, the authors prove the effectiveness of the proposed element in the case where members of H-section adopted in spatial structures are subject to flexural-torsional buckling.