Beauvericin (BEA) is a cyclohexadepsipeptide produced by the fungus Beauveria bassiana. And it has been reported to have very effective anti-cancer activity. However, the mechanistic studies of BEA on cytotoxicity on cancer cells have not been fully understood. In this study, we examined the cytotoxicity of BEA on the C6 (rat glioma cell line). The cell viabilities of C6 cells, MDA-MB 231 (breast cancer cell line), and HeLa (cervical cancer cell line) were decreased by treatment of BEA. In addition, BEA-treated cells showed membrane blebbings and buddings, which indicates that BEA decreased cell viability by inducing apoptosis. Additionally, we found that the level of apoptosis inducing molecules such as caspase 3, caspase 9 of BEA treated cells was increased and apoptosis regulating molecules (Bcl-2) was decreased. We also found that the activated STAT3 and Src was decreased in BEA-treated condition. In further study, we are going to find out how the BEA can influence Src kinase activity.