【Purpose】Human modify a movement depending on sensory feedback to perform the movement correctly. Visual feedback (VF) is especially important, but the effect for muscle activity is poorly understood. The purpose of this study was to investigate the effect of VF for muscle activity.【Methods】Twelve healthy women were recruited this study. The tasks were coordination of knee extensor muscle contraction with VF or non VF. The orders of tasks were randomized.【Results】Themuscleactivitywasmorereduced at VF condition than that of non-VF conditionʼs one.【Conclusion】The results suggested that VF condition reduce excessive muscle activity, because subjects can use not only somatosensory feedback but also visual feedback at VF condition.