When an unsoundness reinforced soil wall was built by some kind of factors, it is necessary to elucidate the mechanism by a detailed field work how deformation occurred, and we must take the measures that a similar phenomenon is not generated in future. This paper is findings to grasp factor of deformation of the geo-textiles reinforced soil wall which did be large deformation. The data which used of the subsidence of a history at the time of the construction, a physical characteristic, the bowling inves-tigation into used laying earth on the ground materials, the rain and ground water level after the construc-tion, the reinforcement domain pass, and is a change at time. We considered factor of deformation of the geo-textiles reinforced soil wall to a base by these data. The point concerned was the topography condi-tion that the rain and melting snow water concentrated on a reinforcement soil wall, and, as a result of in-vestigation, there was it in the environment where the ground water level in the reinforcement domain was easy to rise to by the rain because a substrate was weathering shale, and permeability was low. In ad-dition, internal and external stability were impaired due to the declining interlocking effect of geo-grid and backfill soil. It was presumed that progression of the settlement of the upper part of the reinforced ar-ea by increasing the horizontal displacement of the skin wall.