In the clinical, it is difficult to carry out the motion analysis because it requires a large place. The purpose of this study is to examine the gait analysis method by one direction frontal video that can be easily measured in clinical. The subjects were five healthy persons attached four markers at both shoulders and both anterior superior iliac spine (ASIS). The walking motion of each subject toward a camera was analyzed. Body trunk tilt and centroid sway of the upper body part were calculated and compared with the results of three-dimensional gait analysis methods. The result showed the same tendency of the body trunk tilt and the centroid sway changes based on each method. The result suggested that the gait analysis by one direction frontal video could evaluate the large abnormal gait. Further, authors evaluated OA knee joint thrust using one direction frontal video. The change of the knee joint alignment and the distance between the loading axis of lower extremity and knee joint center were calculated as knee joint thrust. Results showed that knee adduction angle and distance of knee joint center from lower limb loading axis of OA patient were increased. The result suggested that this method could evaluate the knee joint thrust of OA patient.