Centrifuge model tests were conducted to study the behavior of geogrid reinforced embankment during earthquakes. In this study, an attempt was made to discuss the effects of length and spacing of geogrids on the behavior of the reinforced embankment. It was found that displacement of reinforced zone was caused by the combination of sliding and shear deformation of the zone. The larger sliding took place in the case with the short geogrid for reinforcement irrespective with the placing. Spacing of geogrid mainly affected the shearing deformation.