Antioxidant activities of Hericium erinaceum was in vestigated in subfractions of methanol extract such as hexane, chloroform, ethylacetate, butanol and water subfractions. Chlorofrom fraction exhibited the highest antioxidant activity and showed the highest level of total phenolic contents. The level of total phenolics may be correlated with the antioxidant activities of the subfractions. Therefore, the phenolic compound in the chloroform subfractions exhibiting high antioxidant acticity was identified by mass spectrometry using LC-MS/MS. In addition, hot water extract of this mushroom were tested for antimutagenic activity by Ames Salmonellaassay.Thisextractshowed inhibitiory effect on the mutagenesis induced in Salmonella typhimurium strain TA100 and TA98 by the directly actingmutagen 4-nitroquinoline-1-oxide(0.15μg/plate) and sodium azide (0.5μg/plate). The extract also inhibited mutagenesis induced in Salmonella typhimurium strain TA100 and TA98 by the indirectly actingmutagen 2-aminoanthracen(2μg/plate) at 5000μg/plate and 200 μg/plate, respectively.