"SBHS" has been standardized in Japanese Industrial Standards . The major features of SBHS are high yield point, high toughness and better weldability. In some bridges in Japan, SBHS has been already used as steel members. However, the information on the buckling strength of steel members made of SBHS400 is not sufficient compared to conventional steel materials. In this study, the compression tests on welded box section stub-columns were conducted to obtain information on buckling strength of SBHS400. As a result, basic information on the buckling strength of box section stub-columns was obtained. The experimental data indicate the possibility that the previous ultimate strength curves may be applicable to simply supported plates of SBHS400.