In recent decades, lean manufacturing caught the attention of industry and academia. Therefore many researches on the lean transformation have been published. However, the number of researches considering the measurement of the benefit of lean transformation is relatively small. This lack of research caused some hesitation in adopting lean transformation, especially in small and medium sized manufacturing companies. In this research, a simulation model which can measure the benefit of lean manufacturing will be developed so as to compare its benefits under various business environments. Among the various lean transformation tools, this paper deals with the load balancing in a manufacturing cell, which is an essential step in the lean transformation. For the simulation test, system dynamics models which are composed of the process model and the operator model have been developed. Experimental tests comparing the balanced cell with non-balanced cell are performed. Test results are analyzed and some managerial implications are derived from the test results.