The soil adsorption coefficient of butachlor was measured mainly following the guidelines of U. S. EPA and OECD. The soil adsorption coefficient, Koc, of butachlor agreed well with the values in the literature. It was observed that soil adsorption differed about 5% with an increase or decrease by $15^{circ}C$, implying that temperature does affect soil adsorption. The estimated value of the soil adsorption coefficient using water solubility and molecular structure deviated by factors of 2 and 20, respectively. The soil adsorption coefficient, Koc, of butachlor was 543 so this value means that butachlor is tightly bound to organic matter in soil and is considered immobile. A novel trial estimating the soil adsorption coefficient by molecular structure might be utilized to design efficient and/or non-polluting agrochemicals by organic chemists.