The relationship between nitrate-nitrogen leaching and climatic factors was examined with vegetable cultivation under heavy application of fertilizers in Andosol and Yellow soil. Multiple regression analysis was performed with influences of climatic factors on monthly amount of the nitrate-nitrogen leaching. The precipitation influenced most effectively the nitrate-nitrogen leaching in both soils, but air temperature also influenced the leaching in Andosol The values estimated by using the multiple regression equation accorded fairly well with the measured ones. However, the result indicated that it is necessary to take in to consideration the precipitation of the preceding autumn for the assay of the leaching in the spring season .
　The use of chloride-chlorine is effective as an alternative tracer of nitrate-nitrogen. Smooth sigmoid curves between the leaching of chlorine and percolating water were obtained, in which the orthogonal polynominal was applied most effectively.