Background : F. fomentarius extracts have been recently reported to process immune-stimulatory and anti-inflammatory effects. In this study, we evaluated the anti-mutagenic effect of F. fomentarius ethanol extracts and the effective chemical components from the extract were analyzed by LC-Q-TOF. Methods and Results : F. fomentarius was extracted with 70% ethanol yielding a crude extract 6.8%. The crude extract was fractionated sequentially to diethyl ether, chloroform, dichloromethane, butanol and water with a yield of 43.9%, 2.958%, 6.8%, 21.6% and 25.5.%, respectively. The anti-mutagenic effect of F. fomentarius extract and its fractions was tested in Ames test by two type of Salmonella typhimurium (TA98 and TA100). Among the five fractions, diethyl ether has shown the highest and significant anti-mutagenic effect (98.3%, at 3,000 ㎍/plate concentration). Moreover, we investigated the chemical constituents of the extract using UPLC-Q-TOF. A total of 10 compounds such as flavonoids (velutin, 3, 4′,5-Trihydroxy-3′,7-dimethoxyflavanone) and fatty acids (γ-linoleic acid, stearic acid) and deterpenoid (kirenol) were tentatively identified with an accurate mass within 10 ppm mass error. Also, flavonoids and fatty acids were detected with higher rate than other compounds based on obtained chromatograms. Conclusion : We demonstrated that F. fomentarius extract and fractions have anti-mutagenic activity through Ames test. Furthermore, we will carry out isolation of each components from its fraction and use them to conduct additional anti-mutagenic test.