Magnesium alloy sheets have an excellent light weight property. Therefore, they are expected to be used in automotive and electronic industries. However, magnesium alloys have unique mechanical properties such as high in-plane anisotropy/asymmetry in yield stress and hardening behavior. In this paper, the change in elastic modulus caused by cyclic loading has been measured and the resultant parameters have been figured out. In this process, a recently developed tension-compression tester was used. In the cyclic loading test, elastic modulus tended to decrease as the strain got stronger. Based on the tendency, springback prediction was made.