In search for plant-derived cytotoxicity compound against human cancer cells (A549, SK-OV-3, SK-MEL-2, XF498, HCT15), it was found that the chloroform extracts obtained from the whole plant of Carpesium rosulatum MlQ. (Compositae) exhibited significant cytotoxic activity. Four sesquiterpene lactone, CRC1 (2α, 5-epoxy-5,10-dihydroxy-6-angeloyl-oxy-9β-isobutyloxy-germacran-8α,12-olide), CRC2 (2α,5-epoxy-5,10-dihydroxy-6α,9β-diangeloyloxy-germacran-8α,12-olide), CRC3 (2α,5-epoxy-5,10-dihydroxy-6α-angeloyloxy-9β-(3-methyl-butanoyloxy)-gemacran-8α,12-olide), CRC4 (2β,5-epoxy-5,10-dihydroxy-6α,9β-diangeloyloxy-germacran-8α,12-olide) were isolated from the whole parts of C. rosulatum. 2α,5-epoxy-5,10-dihydroxy-6α,9β-diangeloyloxy-germacran-8α,12-olide (CRC2) showed the most potent cytotoxicity with IC(50) value of 6.01 μM against SK-MEL-2.