In order to obtain basic data for utilization of the aerial parts of Cnidium officinale Makino (APCO), the antioxidant properties of the aerial parts and rhizomes of C. officinale were measured using DPPH and ABTS radicals, and nitrite scavenging assays. The ethyl acetate (EA) fraction prepared from the aerial parts of APCO showed the strongest antioxidant activities, and contained high level of total phenolic compounds (325.81 mgTE/g) and flavonoids (259.16 mgRE/g). The concentrations for 50% reductions (RC50) values of the DPPH and ABTS radicals, and nitrite by the EA fraction of APCO were 11.27 μg/ml, 14.34 μg/ml, and 10.26 μg/ml, respectively. APCO exhibited approximately 3-9 times higher antioxidant activity than rhizomes of C. officinale. The antioxidant capacities of APCO were positively correlated with its total phenolic contents. Therefore, it was concluded that the aerial parts of C. officinale can be a useful and cost-effective source of natural antioxidant for food or cosmetics.