The $ABTS^+$-radical-cation scavenging activity, DPPH radical scavenging activity, ferric reducing/antioxidant power, and nitrite scavenging activity of the methanol extract from Hericium erinaceum and its subfractions were assessed. Among the methanol extract subfractions tested, the chloroform subfraction exhibited the strongest antioxidant activity in the most experiments, except for the ferric reducing/antioxidant power. The Trolox equivalent antioxidant capacity (TEAC) of the chloroform subfraction was 378.89 ${mu}mol/g$ of sample. This subfraction also scavenged 35.80% of DPPH radicals at 500 ${mu}g/mL$. The highest ferric reducing/antioxidant power was found in the n-hexane subfraction (174.82 ${mu}mol$ $FeSO_4{cdot}7H_2O/g$). The chloroform, n-hexane, and n-butanol subfractions had high total phenolic compound content, with ferulic acid equivalents of 35.18, 19.08, and 11.23 mg/g, respectively. Flavonoids were found mostly in the chloroform subfraction, and the 4 phenolic compounds were identified in the same fraction as 4-hydroxybenzoic acid, syringic acid, 4-coumaric acid, and ferulic acid by electrospray ionization (ESI) LC-MS/MS analysis.