The aerial part of Artemisia iwayomogi Kitamura has traditionally been used for inflammation, infectious disease, cancer, pyretic, diuretic, liver protective effect, and choleretic purposes in Korea. We investigated that the essential oil induces apoptosis in KB cell as evidenced by Hoechst-33258 dye staining, flow cytometry (cell cycles), and DNA fragmentation for nuclear condensation and Western blotting for activation of caspases-3, -8, -9, Bax, Bcl-2, cytochrome c, and poly (ADP-ribose) polymerase (PARP) cleavage. In the present study, we found that the essential oil could induce apoptosis in KB cells, as characterized by DNA fragmentation, activation of caspase-3, -8, and -9, and PARP cleavage. The efficacious induction of apoptosis was observed as a dose-dependent. The essential oil-induced apoptotic cell death was accompanied by up-regulation of Bax and down-regulation of Bcl-2. The essential oil also caused the loss of mitochondrial membrane potential and cytochrome c release from mitochondria to cytosol. These findings indicate that mitochondrial pathways might be involved in the essential oil-induced apoptosis and enhance our understanding of the anticancer function of the essential oil in herbal medicine.