The purpose of this study was, to estimate the detergency of commercial detergent and to examine the interrelationship between detergency and detergent characteristics, detergent concentration, fiber characteristics, and Rolling-up phenomenon which is the major removal mechanism of oily soil. A mixture of oleic acid-olive oil was used as oily soil. The detergency was estimated by analysis of oleic acid on cotton ana polyester fabrics before and after washing by means of liquid scintillation counting. The Rolling-up of oily soil from PET film was observed and change of contact angle and removal time were measured. The results were as follows ; 1. In the case of soaps and powder synthetic detergents, the optimum concentrations we-re about $0.2~0.3\%$. And detergencies of liquid synthetic detergents were considerably low, and the detergency was continually increased up with increasing concentration to $0.5\%$, which seemed to be caused by the lower pH than that of soap and powder synthetic deter-gent solutions. 2. As the effect of external or internal fiber structure; the detergency of cotton was lower than that of polyester. 3. In the observation of Rolling-up, the contact angle increased and the Rolling-up time became shorter with increasing detergent concentrations ($0.05~0.5\%$). And it was confirmed that detergency was increased with Rolling-up effect. In addition, the study on the actual laundry condition was studied using the questionaire. From the results, about $76\%$ of households used the concentration of detergent roughly or excessively and housewives were highly concerned on the recommended dose, but grade of practice were very low.