Abstract: There are provided a method for predicting a springback amount and a method for bending a deformed reinforcing bar including: supplying the deformed reinforcing bar bending the supplied deformed reinforcing bar, and subsequently measuring a first bending angle in a state of releasing a bending force on the deformed reinforcing bar; further bending the reinforcing bar from which the bending force has been released, and subsequently measuring a second bending angle in a state of releasing the bending force; and predicting a relationship between the bending angle and the springback amount by using the measurement results after executing the further bending once or a plurality of times, in which the bending angle is greater for subsequent steps.