We examined the intracellular growth of Listeria monocytogenes strains with macrophage-like cell line J774-1. Mouse pathogenic strains were found the intracellular growth, while non-pathogenic strains were not found the growth in five hours after inoculation. Accordingly, it is suggests that virulent examination with the cell line is available. Moreover, two virulence-associated genes (hlyA and plcA) were detected by PCR technique. As a result, the nonvirulent standard strain ATCC15313 defected both hlyA and plcA genes, the non-virulent strain RM3-1 isolated from cattle raw milk was detected these genes. Therefore, this suggests that virulence-related mechanism of RM3-1 strain is different from ATCC15313.