A high manganese content deformed reinforcing bar having an austenite single phase microstructure has excellent bending workability. A deformed reinforcing bar includes a chemical composition containing, in mass %, C: 0.7% or more and 1.2% or less, Si: 1.0% or less, Mn: 9% or more and 15% or less, Cr: 1.0% or less, P: 0.03% or less, and S: 0.05% or less, the balance consisting of Fe and inevitable impurities; and a microstructure comprising an austenite single phase. The ratio of the difference between the maximum and minimum hardness at a periphery of a cross-section perpendicular to the longitudinal direction with respect to a central average hardness is 15% or less. Two or more ribs extend in the longitudinal direction at equal intervals in a cross-sectional circumferential direction. The ratio of the difference between the maximum and minimum width of the ribs to the minimum width is 50% or less.

Reinforcing is disclosed comprising a reinforcing bar extending along a portion of the length of the reinforcing and a termination extending along an end portion of the reinforcing. The termination may have a body extending in a longitudinal direction and a lateral engagement face formed on the body. The engagement face may incorporate locking formations thereon arranged to interfit with a complementary shaped termination to form an interlock arranged to accommodate loading applied in the longitudinal direction.