Stress-strain rate data of the Pb-Sn eutectic alloy specimens were obtained from differential strain rate and stress relaxation tests. The data were found to differ from each other in the higher temperature range in some cases. This discrepancy could be accounted for in terms of the anelasticity effect on the relaxation behavior by means of the rheological model of H. Schneibel and P. M. Hazzledine. Since the internal stress measurement by the stress dip test may also be affected by the anelasticity, a method of checking whether the internal stress thus measured is a consequence of the anelastic effect or not is proposed on the basis of the rheological model of Schneibel and Hazzledine.