This investigation, which was done by bending and subsequently straightening the bars, was carried out in order to study the bending characteristics. To avoid bending fracture in bend and return process, the bar temperature should be above 0℃ and the radius of curvature should be more than 4 × D_0 (D_0=indicated bar diameter), except for bars with c/D_0<0.031 (c=radius of ribs bottom curvature). An increase of carbon equivalent, nitrogen contents and sulfur contents are related to an increase in breaking rate of each bar. Stress concentration factor, which is a function of the bar shape properties, also affects the breaking rate.