Dispersion coefficients D resulting from Tsukuba soil-picric acid leaching system showed a large variance, but they had a tendency to increase with the pore-water velocity U, representing the regression equation D=0.46U-0.053, U>0.1cm/min. D seemed to be independent of U below 0.1cm/min and the average was 0.012cm²/min. A 3cm length soil column showed two peaks before and after the simulation peak, while a 27cm length soil column showed one peak before the simulation peak. This phenomenon is explicable by the wall effect. Konosu paddy soil-picric acid system resulted in 0.14cm²/min of D independent of U. The Freundlich's adsorption coefficients of picric acid and oxamyl were 3.84 and 0.33 in ppm unit and the indexes were 0.816 and 0.828, respectively. Tsukuba soil-oxamyl leaching system gave 0.008cm²/min of D at a low U 0.06cm/min, which was the similar value as Tsukuba soil-picric acid leaching system. This suggests that the soil types affect more greatly on the dispersion coefficient than the kind of leached chemicals.