In cold, snowy regions, the gabion work has been often done as emergency or restoration measures against surface layer failures of the cut slopes arising from frost heaving or freezing-thawing. There has been developed a reinforced soil wall that has the gabions as walls and is reinforced with woven metallic wires integrated with gabions. This reinforced soil wall is expected to become popular as a reinforced soil wall suited for the cold regions, due to the high degree of drainage and following capability of the gabions. In this paper, based on the analysis of seepage flow, evaluation was made on how the change in capacity of drainage system to lower the water level in backfills affects the water level in the backfills. The result of seepage analysis of demonstrates that the drainage blanket works effective for lowering the groundwater level in backfills.