In recent years, body weight support (BWS) systems have been applied and have played an important role in most of the gait training systems. Conventional BWS systems commonly use the rope–pulley mechanism such that the “pendulum effect” generated during gait training would cause discomfort to the subject. Our hypothesis was that the center of mass (COM) parameters in the lateral and vertical directions of the subject during walking under a weight support system would be modified. Moreover, the novel BWS system that was developed would reduce the “pendulum effect” during walking and exhibit an enhanced behavior in comparison with the counter weight system. Our findings revealed that the step width and the COM amplitude in the mediolateral and vertical directions in the cases using the new BWS and counter weight systems were significantly smaller than those for the normal walking case. The COM amplitudes obtained when using the new BWS were closer to the normal walking case and higher than the counter weight system.