No earthquake has caused failure or severe damage to any rockfill dams with bodies of well-compacted rock materials. It is important to estimate the damage grade quantitatively in order to evaluate a seismic performance of a dam against a large earthquake. A centrifugal shaking model test of a rockfill dam was performed under centrifugal force field of 50g to investigate the seismic damage patterns of rockfill dams. The shake-induced deformation from sinusoidal wave shaking was limited to the high elevation rock zone near the slope top and the upper core. This shaking model test did not cause any deep failure surfaces. The dam behavior caused by the shaking test was simulated by the elasto-plastic effective stress analysis incorporating a constitutive equation which can simulate the cyclic mobility of compacted rock materials. The analysis succeeded in reproducing most of the state of deformation in the core and high elevation zone of the upstream rock.