Inhibitory mechanism of colored rice bran against cellular genotoxicity induced by chemical mutagen was studied using organic solvent extracts from a colored rice cultivar termed as Suwon415, and the mutagen, mitomycin C. Inhibitory effects of 70% ethanol extact and chloroform fraction from rice bran of Suwon415 were higher than those from Chuchung used as control. However, antioxidative activities of each fraction from Suwon415 were slightly lower than those from Chuchung, suggesting the involvement of a different inhibitory mechanism not related to antioxidation pathway. Using E. coli as the indicator cell, inhibitory mechanism of rice bran extract from colored rice against mutagenicity induced by mitomycin C was investigated to reveal the possibility that it acts in a desmutagenic manner. Further investigation to quantify the free mitomycin C in reaction mixture following incubation with rice bran extract demonstrated that rice bran extract might inhibit the cellular genotoxicity of mitomycin C by direct adsorption of the mutagen.