The invention relates to a medicament, namely a medicament for treating cancer, also relates to a compound with the actions of inhibiting and killing cancer cells and also relates to a Mongolian medicine extract with the anticancer effect. The medicament is characterized in that the medicament is a monocyclic sesquiterpene compound, the monocyclic sesquiterpene compound is an isomer of C15H22O2, C15H22O, C15H24 or C15H22O2 and is an extract of leayjerleaf cloves, serving as a Mongolian medicine. The medicament has the beneficial effects that the medicament is exact in effect of treating the cancer as having obvious actions of inhibiting and killing various cancer cells and is small in side effect to a human body without pains in the medication process; particularly, the compound can be extracted from the leayjerleaf cloves, serving as a Mongolian medicine, is easy in raw material acquisition, simple and convenient in method and low in cost, is capable of hopefully and remarkably lowering the curative cost and has the important significance of reliving pains of a patient with the cancer, increasing the health level of people and improving the life quality of the people.