Human dynamical balancing capability is affected by physical exercise and aging. Although the deterioration of this capability sometimes causes accidents and falls, the precise mechanism of this capability has not been clarified. Thus, we are creating a measuring and training device to determine the level of this capability, improve patients' physical condition, and help them prevent losing any further physical strength. In this study, we designed and created a prototype for a new device that is different in structure from our previously developed device in order to enhance the multiplicity of training. The new device is based on use of a pair of small-sized "two-parallel wheel sub-vehicles," and these two sub-vehicles can be connected to each due to the computer control. Through experiments, we investigated the behavior of trainees with this device, and examined the possibility of the device being used for measuring and training purposes.