The antioxidative effect and antimutagenic capacity in ethanol extracts of Lentinus edodes were studied for suggestion of prevention and dietetic treatment of chronic diseases and development of antioxidative and antimutagenic functional food by employing biological and biochemical assay. The $IC_{50}$ of MDA with BSA conjugation reaction, lipid peroxidation and scavenging effect on DPPH radical in ethanol extracts of Lentinus edodes showed 74.58 mg/assay, 5.747 mg/assay and 0.939 mg/assay respectively. So, the most effective antioxidative capacity in ethanol extracts of Lentinus edodes was the scavenging effect on DPPH radical, among the method used this study. The indirect and direct antimutagenic effects of ethanol extracts of Lentinus edodes were examined by Ames test using Salmonella typimurium TA98 and TA100. The inhibition rates on indirect mutagenicity mediated by 2-anthramine showed 91.67% in the Salmonella typimurium TA98 and 96.60% in the Salmonella typimurium TA100. The inhibitory effect on direct mutagenicity mediated by sodium azide in Salmonella typimurium TA100 was 22.83%. and mediated by 2-nitrofluorene in Salmonella typimurium TA98 was 5.34%. This data indicates that ethanol extracts of Lentinus edodes have more effective effects on indirect mutagenicity than direct mutagenicity. From this result, it believed to have a possible antioxidative and antimutagenic capacities, and taken for the candidate of prevention and dietetic treatment of chronic diseases and development of antioxidative and antimutagenic functional food.