The Bureau of Divination was made up of divisions dealing with Ommyodo, Tenmondo (the art of divination by observing the movements of the sun, moon, stars and planets, and the weather), and Rekido (masters of the almanac) these three divisions performed divination, observed the movement of the sun, moon, and stars, and created a calendar.
陰陽寮は配下に陰陽道、天文道、暦道を置き、それぞれに吉凶の判断、天文の観察、暦の作成の管理を行わせた。