Tubular sections are commonly used for truss structures or diagonal braces, because they have higher moment-of-inertia comparing to open cross-sections with the same area. However, their cumulative cyclic deformation capacities after buckling are known as quite small comparing to H-sections, because strain concentration occurs with local elbow buckling. For evaluating seismic performances of such structures, cumulative cyclic deformation capacity of braces before fracture is essential. In this paper, cumulative cyclic deformation capacity of tubular braces with local buckling is researched by cyclic loading tests with various slenderness ratios and thickness ratios. Their strain concentration mechanism is researched thorough various analyses, followed by proposing easy evaluation method of cumulative deformation capacity.