To determine whether the toxicity of Bacillus cereus would be seen in human cell lines and mice, we screened B. cereus B-38B, B. cereus B-50B, and B. cereus KCCM40935 for genes that coded for 5 enterotoxins using the polymerase chain reaction and cultivated them for 17 hr, by whose time they had grown to $10^7-10^8$ colony-forming units (CFU) per milliliter. Cell-free supernatant was added to make up 1% of the total reaction solution. Human cells from normal lung, lung carcinoma, embryonic kidney, and cervical adenocarcinoma cell lines were grown in culture. The cytotoxicity induced by adding the reaction solution was indicated by cell death rates of 0 to 70%, depending on the bacterial strain involved and the cell line. A lethality of 20% was observed when B. cereus cultures containing $10^7-10^8$ viable cells were administrated orally to mice. Therefore, the culture of B. cereus containing $10^7-10^8$ viable cells seems to have high cytotoxicity on human cell lines and lethality on mice.