In order to avoid brittle failures of welded box section steel members, cold pressbent rounded corner is effective. Considering effects of cold forming and strain aging, the use of SBHS, which has guaranteed higher toughness than conventional steels is suitable. In this study, material properties of cold press-bent SBHS400 were experimentally investigated. In addition, axial compression behavior as an unstiffened stub-column was examined both experimentally and analytically. As results, cold press-bent SBHS400 has enough toughness and the changes of mechanical properties are similar to those of conventional steels. The analysis results show that the difference in residual stress distribution largely affects on the load-carrying capacity of stub-columns.