In this paper, we calculated the angle of gait based on the image of markerless single depth camera and detected the gait state from the front. First, the silhouette image is extracted from images which are obtained by depth stream and it generates a chain code about a set of pixel values of the edge. Second, the gait angle is derived from depth information that is acquired by the three feature points on the lower body from the chain code. We are performed gait state analysis using DFT from autocorrelation of gait angle. Perhaps some results of the markerless gait analysis can use their application even in a confined space.