This paper deals with the results from stability analyses of geogrid reinforced roaa- embankment that remains without any damage during Kushiro Offshore Earthquake (1993; M7.8) in Japan. The earthquake’s epicenter was located approximately 33 km· from the embankment, and the horizontal acceleration at the embankment site is estimated at 310 gal. The embankment under study has the following features: height: 5.5 m, angle of face slope: °
73.3 , reinforcement: geQgrid of type SR-55, wall face material: expanded metal, height of upper unreinforced embankment section: 1.2 -m and designed by Jewell et al.’s method at ordinary condition. The analyses are conducted according to the seismic design method of the Public Works Research Institute compared with the method of Geogrid Research Board. From these analyses:; the seismic efficiency of geogrid reinforced structure is evaluated.