The hysteretic behavior of reinforced concrete bridge columns depends on the hysteretic behavior of reinforcing bars. The model proposed by Giuffre, Menegotto and Pinto has been widely used as a nonlinear hysteretic model for reinforcing bars because of its simple but accurate expressions. However, the model often develops an unrealistic sudden change of the stiffness resulted from partial unloadings and reloadings. In such cases, the Bauschinger effect cannot be represented. A modified model for the original Giuffre, Menegotto and Pinto model is proposed by Eqs. (10), (11) and (19) so that realistic hysteretic stress vs. strain relations after partial unloadings and reloadings can be evaluated.