The purpose of this study is to find the canons of the Buddhist monastic architecture in the final phase of the Anuradhapura Period (684〜993 A.D.)in Sri Lanka. This paper analyze the length of the ruler used for architecture. I examined the measurements of stone moldings of the base etc. of 5 pasadas in Anuradhapura, found the greatest common measure was about 8(average 8.18)mm, and resulted the digit was supposed about 33(8.18×4)mm and the cubit about 790 mm(24 digits). This is almost same as the carpenter's cubit of about 790 mm in the Kandyan Period(1592〜1815).
