The purpose of this study is to investigate the backstaining generated during cellulase treatment for indigo-dyed denim. The results were as follows. 1. High generating conditions of the backstaining were as same as best conditions for cellulose activity (temperature at 6$0^{circ}C$, pH at about 4.5~5.5, treatment time at 40 min. and enzyme concentration at 2g/l). And also, liquor ratio, sample weight and repeated-use cycle of liquor had influenced on the backstaining. 2. The backstaining was decreased about 30~40% when various additives, that is, surfactant, anti-backstaining agent (C.M.C) and softners were added. 3. A application of image processing on the backstaining evaluation was more effective than method by reflectance, particullarly in out of level fabrics. In image analysis, the backstainings were measured by histogram between 256 gray levels.