A buckling restrained brace includes an axial member and a restraining unit. The axial member extends along an axial direction, and has two coupling sections for connecting respectively to two connecting plates of a framework of a building, and a middle section connected between the coupling sections. Each coupling section has a supplying plate portion coplanar with an elongated plate body of the middle section, and a contacting plate portion extending perpendicularly from the supporting plate portion. An outer end of the supplying plate portion of each coupling section has a groove formed therethrough along a transverse direction of the axial member, extending along the axial direction, and permitting a respective one of the connecting plates to engage fittingly therewith and contact the corresponding contacting plate portion.