Objective of this study was conducted to assess the effect of leachate from the landfill area to quality of surface water, shallow deep water and well water in the paddy. Landfill area of municipal waste that had been used from 1982 to 1995 was 81,000 m3 with 25 m of landfill height and had 10 ha of rice paddy surrounding it. These paddies had used the irrigation water from several wells below the landfill area. Water samples were collected from 5 sites that had distributed with proper distances, and analyzed the water quality through the cultivation periods. For the water quality assessment method, relative risk assessment index of parameters was calculated with dividing an observed values in sampling sites into observed values in the check site for surface and shallow deep water, and with dividing their observed values into guideline values for agricultural irrigation quality for well water. In respective to the chemical properties of leachate from landfill area, CODMn in drought season was decreased at 1.9 fold as compared to the rainy season. However, it was observed that NO2-N and Cl concentrations in drought season were increased at 3.1 and 2.7 times relative to the rainy season, respectively. Considering about characteristics of water quality in the rice paddy surrounding the closed landfill area, it observed that Cl and Al concentrations in the surface water and CODMn, Mn, Cl, Al and Mn concentrations in the shallow deep water were higher than those of the check site. CODMn, Mn, Cl, Al and Mn concentrations in the well water were exceeded the guideline values for agricultural irrigation. It appeared that predominant species such as Al, Fe and Mn might be attributed for the relative risk assessment index of parameters for water quality.