Introduction: Early detection and removal of the Brucella abortus have been received attention because the bacteria can invade into the professional and non-professional phagocytes, and survive through its intracellular abilities. In this study, B. abortus mutant strains were generated using transposon mutagenesis and the B. abortus wild and mutant strains were analyzed using professional and non-professional phagocytes, RAW 264.7 and HeLa cells to demonstrate the interaction, differences between internalization ability. Methods: RAW 264.7 and HeLa cells were each grown in 2 x 105 cells per well in 24-well plates and infected with the B. abortus wild and the mutant strains at a MOI of 1: 100. Then, a number of invaded bacteria was confirmed using cell lysis and plating on to brucella agar after cells were incubated in each complete media with gentamicin (30 μg /ml). Results: All of B. abortus wild and 28 mutant strains were invaded into RAW 264.7 and HeLa cells showing different invasion efficiency among the Brucella strains according to the cells. For example, wild strain showed highest invasion ability among the 29 strains in RAW 264.7 cells although it showed average efficiency in HeLa cell. The results suggesting that invasion ability may depend on the genetic characteristics and mutagenized characteristics appeared to have different rate when mutants invade into cells. Conclusion: Different invasion rate of B. abortus wild and mutant strains showed in the RAW 264.7cell and HeLa cell. It could be persuasive that the gene mutation by single insertion of Tn transposon could affect on various characteristics of B. abortus, such as invasion rate and biological properties, and additional researches to reveal these changes might be required. This work was supported by NRF (No 2014R1A2A2A01007291), the BK21 PLUS program for Creative Veterinary Science Research and the Research Institute of Veterinary Science, Seoul National University, Korea.