We have demonstrated effectiveness of shortening of display latency on head tracking system and displaying visual information at time of changing motion direction on stable depth perception from monocular motion parallax. We also have shown that smooth motion parallax even at fixed head improves perceived depth degradation caused by decreasing visual acuity of one eye. In this paper, we discussed importance of motion parallax information on both monocular and binocular depth perception, and utilizing motion parallax for realizing more effective 3D display methods.