Long-term stability of two types of geogrids were evaluated. Membrane drawn type geogrid showed an exponential increase in strength on drawing, while textile type geogrid showed sigmoidal increase. Accelerated creep test was carried out for textile type geogrid but not for membrane drawn type geogrid because of its thermal property. Creep strain for membrane drawn type geogrid was larger than the ultimate tensile strain in tensile tests. Reduction factor from creep deformation of textile type geogrid was smaller than that of membrane type geogrid. From this result, it was seen that the textile type geogrid is more stable than membrane type geogrid in creep deformation.