This paper presents an experimental investigation of the influence of different inside and outside diameters relative to the response and collapse of SUS 304 stainless steel tubes subjected to cyclic bending. In this study, three different inside and outside diameters of SUS 304 stainless steel tubes were used. Based on the sizes of the tubes, the tubes were named large, middle and small tubes, respectively. To remove the influence of the out-side-diameter/wall-thickness ratio (D(subscript o)/t ratio), the outside surfaces of the three different tubes were machined to obtain the desired Do/t ratio (D(subscript o)/t =40 is used in this paper). The ”bending testing machine” and the ”curvature-ovalization measurement apparatus” were used to test the tubes' behavior under the loading of cyclic bending to collapse. It can be observed that the SUS 304 stainless steel tube demonstrates a cyclic hardening phenomenon from the moment and curvature relationship, but a steady-state loop of the moment-curvature curve is found after a few loading cycles. It can also be observed that the relationship between the ovalization and curvature demonstrates a symmetric ratcheting, and the ovalization increases when the number of cycles increases. In addition, although three different inside and outside diameters of the SUS 304 stainless steel tubes were tested, three parallel straight lines (corresponding to three different sizes of the steel tubes) of relationship between the controlled curvature and number of cycles to produce buckling were found on a log-log scale.