The purpose of this study was to investigate the effect of differences of the foot center of pressure in standing on postural control of stand-to sit movement. It was thought that the reverse reaction phenomenon of standing posture in normal subjects at the fist of the sitting movement start by reduction of the muscle activity of the lumbar back muscles. Stable stand-to-sit movement was able to be performed when COP was located forward. From this, the position of foot COP in standing before stand-to-sit movement influences the difficulty of adjustment of COP and COG. Therefore, we suggest that in order to improve stand-to-sit movement, it is important to evaluate foot COP in the standing posture and muscle activity of the lumbar back muscles.