8hydroxyodoroside a

An antitumor agent containing at least one compound selected from the group consisting of nerigoside, oleandrigenin, sarmentoside, oleaside A, oleandrin, 8β-hydroxy odoroside A, narciclasine, trans-dihydronarciclasine and bisdeoxynarciclasine is provided, this antitumor agent has an advantage of having an excellent therapeutic effect of tumor and less side effects.