Daylighting in buildings has been discussed in the various fields in terms of its pleasantness in the room and effective use of natural resources. This paper proposes a new type of venetian blind which slat angles are different to guide daylight into the interior, indicates how to fix the angles of each slat, and verifies the effect of daylighting by an experiment and computer simulations. Using this blind, it would be possible to introduce daylight into the interior zone effectively. Furthermore, the luminance values on the window, intensity of the shadows, and illuminance values by the window would be restrained.