A number of closed (uncontrolled) landfill sites are located in the nation-wide, but proper remediation of closed landfill is not performed enough for that of all uncontrolled landfill. Therefore, we want to set a method of assessment for the potential environmental problems in uncontrolled landfill because we require a reasonable tool in making priority for effective management and remediation of closed landfill depending on a small budget. Case study was carried out to the closed landfills located in Gyeong-gi and Gang-won, Chung-buk province. Four sites were excepted because of difficulties in remediation process. The three sites were already remedied and one site was used to industrial complex of rural areas. The ninety-eight closed landfill sites are symmetric regard on the risk priority-point range 50 to 60. Which were classified three categories according to risk assessment priority-point as follows. : Thirty-two landfill sites were found requiring urgent countermeasure since they are important to conserve natural water quality, sixty-five sites were found requiring intense observation and one site was found almost not requiring monitoring. In this study, we should identify the environmental affecting level assessment method for closed landfill. Each site was bored into and landfill gas and leachate from the deep of landfill were analyzed. In addition, water quality of leachate from the well, groundwater, and up- and down-stream around landfill was analyzed in three landfills that were selected by risk assessment priority-point. From the analysis result of stream- water, groundwater, leachate, and landfill gas, this environmental risk assessment method was relatively reasonable.