The aim of this paper is to establish a design system of shading windows which achieve balanced flow of visual, information between the inside and the outside of a room. For this purpose, the relationship between the visibility of a human face, which is common both in the inside and the outside, through a lace curtain, which decreases the luminance of visual target, and the visual factors of the visual taget must be made clear. In this paper, the visibility of a human face was classified into the visibility of exsistence, the visibility of outline, and the visibility of detail, considering the visual factors corresponding to each visibility. Then, the experiment on the subjective evaluation was done under the conditions which were limited to the extent of actual situation. It was ascertained that the visibility of existence and outline were corresponded to the visual factors, that is the visual angle for the size of a human face, the luminance of background, and the luminance contrast between the luminance of the background and the hair. It was also ascertained that the visibility of detail was corresponding to the visual factors, the visual angle on the size of a human face, the luminance of cheek, and the luminance contrast between the luminance of the cheek and the eye.
