본 연구는 편백정유의 천연 항산화제로의 유용성을 평가하기 위하여 수행했다. 편백정유 원액과 편백정유 분획물의 항산화활성을 1,1-diphenyl-2-picrylhydrazyl (DPPH)법과 ammonium thiocyanate법을 사용하여 조사하였다. DPPH법을 이용한 경우 편백정유의 IC50은 40 ㎕/㎖였으며, 편백정유 분획물 중에서 G분획의 DPPH 항산화능이 0.5 ㎕/㎖ 농도에서 66.94%로 가장 높았다. Ammonium thiocyanate법에서 배양 1일 후 편백정유 원액과 편백정유 분획물 C, D, E의 항산화효과는 각각 72.0%, 71.2%, 71.9%, 71.0%였다. 항산화 활성분획인 G분획은 α-terpineol, elemol, widdrol, α-cadinol 등으로 구성되어 있었다.This study was carried out to investigate the potential promise of Chamaecyparis obtusa oil as a natural antioxidant. C. obtusa oil and its fractions were subjected to screening for their antioxidant activities by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and ammonium thiocyanate method. In the first case, IC50 value of the C. obtusa oil was determined as 40 ㎕/㎖. At 0.5 ㎕/㎖ concentration level, free radical scavenging effect of fraction G determined as 66.94% was the highest among the fractions of C. obtusa oil. In the ammonium thiocyanate method, essential oil of C. obtusa and its fraction C, D, and E showed activities of 72.0%, 71.2%, 71.9% and 71.1%, respectively. Fraction G, most active fraction, was mainly consisted of α-terpineol, elemol, widdrol and α-cadinol.