In this study, we developed a method that target cells in suspension can be separated by combining magnetic force and gravitation force. Since the newly developed method involves a separating process of a droplet containing nontarget cells in suspension by applying magnetic force to separate target cells, we called it droplet-based magnetic activated cell sorting (dMACS). To demonstrate the efficiency of the dMACS system, Ter119 (+) cells from mouse bone marrow cells were separated by both conventional MACS and our dMACS systems. Effects of three parameters on separation efficiency were examined in the dMACS system. As a result, both volume of droplet of cell suspension, and magnetic force did not affect the efficiency of cell separation markedly. However, the time for cell settlement in the droplet showed a critical role in the efficiency of cell separation according to increasing time. Therefore, we tried to verify that the saturation time affected increase of its efficiency and that flow rate injected to get rid of the negative cell resulted in the decrease of its efficiency. Using this dMACS system, we were able to pinpoint that the flow rate of cell suspension injected into a magnetic platform results in disturbance in the droplet, leading to turbulence in the cell suspension.