The authors developed a buckling‐restrained brace for using steel framed houses．The buckling‐restrained brace is small‐sized and light‐weighted with a restraining part of hard polyurethane or mortar．Conducting static and cyclic axial loading tests，elastoplastic and stiffening properties are difined．Specimens with the restraining parts of various restraining forces were fabricated．The authors considere the test data on cumulative ductility factors and cumulative plastic strain energy，and evaluate its performance
