A study on fate and behavior of endosulfan, which is an organochlorine insecticide detected mainly in Korean soil, is important due to its toxicity and persistence in soil environment. To estimate isotherms for the adsorption of endosulfan isomers (α-, β-) and their metabolite (-sulfate) in soil, their adsorption amounts were investigated in various soils containing different organic matter contents. The tested soils were collected at Ansim and Gunwi, and some of them were prepared as organic matter-removed (OMR) samples using H2O2. As time-dependent adsorbed amounts of endosulfan reached to their equilibrium after 6 h in Ansim, Gunwi and OMR Ansim soils, OMR Gunwi soil did not adsorb the pesticide within 24 h. The adsorption isotherms of endosulfan isomers and their metabolite fitted to Freundlich adsorption isotherms for three equilibrated soil samples. The correlation coefficients (R2) of the isotherms were greater than 0.964. Freundlich adsorption coefficient (Kf) ranged from 8.66 to 19.20 for α-endosulfan, from 7.08 to 20.49 for β-endosulfan and from 8.62 to 17.98 for endosulfan-sulfate, respectively. The difference of Kf values of endosulfan indicated that the adsorption amount of endosulfan was dependent on the contents of organic matter. Therefore, the behavior of endosulfan in soil environment is definitely affected by the amount of organic matters in soil.