To increase the transmission efficiency of incoming and outgoing light on the side of a transparent resin light guide, such as an acrylic plate, we created a machined surface that does not become cloudy and transmits visible light well by cutting it with a single crystal diamond tool. When light is guided to this mirror-finished acrylic plate using an LED light source, its uneven brightness or illuminance distribution may be noticeable, depending on the application. To suppress the uneven distribution, attempts have made the luminance distribution uniform by a decorative cut on the acrylic plates for a fine pattern shape. Our research is developing a light environment design support system using an acrylic light-guiding plate with a decorative cut surface. This system consists of a rapid decoration pattern design technique with optical simulation, a decorative cutting technique to satisfy the demanded optical characteristics, and a technique to maintain machining quality. We implemented decorative cutting tests for various stripe patterns by adjusting the cutting conditions for the acrylic plates. Estimation of the decorative shapes was based on the shape of the tool cutting edge and its trajectory. We controlled the decoration shape and dimensions. The tendency of luminance distributions estimated by optical simulation were corresponded with the actual distributions.