In so far as stance is maintained during various activities, the center of pressure must be maintained with a certain area. This area is the range of the center of pressure. It is influenced by standing conditions and vision. In this study we used a force platform to measure the range of the center of pressure in 10 normal adults during maximal voluntary shifting from right to left, back and forth under 6 conditions (standing conditions: both legs apart, both legs together and standing on one leg; vision: eyes open and eyes closed). We also recorded the center of pressure while standing still for 30 seconds under the above 6 conditions. The scatter of the center of pressure and the range of the center of pressure were compared. Under easy standing conditions, the range of the center of pressure was very large and the center of pressure was concentrated in a small area. The more difficult the standing condition, the smaller the range of the center of pressure, and the wider the scatter of the center of pressure. Under very difficult standing conditions, the range of the center of pressure was almost as large as the area in which the center of pressure was scattered. Since the range of the center of pressure is closely connected with the scatter of the center of pressure, it may be possible to determine the accuracy of stance regulation by analyzing the range of the center of pressure and the scatter of the center of pressure.