Design about the eaves is a very important factor to construct exterior on Japanese traditional architecture. In the Edo and Meiji era, many Japanese architectural books were written. But eaves camber design method was not written until "Banshouke Kayaoisori Mitugousinri" which was written by Tousai Kiko in 1864. After that, 12 books were written. We universalize these methods by functional equations, and attempt to make practicable by CAD. We examine the rate of application for architectural monuments by computer analyzing, and propose "Formula of Eaves Camber for CAD" as best formula.