The Yoro ritsuryo code (code promulgated in the Yoro period) described that its major duties were 'taking out of and putting in a storage, denso (rice field tax) of various provinces, shomai (white rice which was the base unit in the fiscal administration under the Ritsuryo system), and tengai (mill powered by the water).'
養老律令によれば、主な職務は「倉廩（倉庫）の出納、諸国の田租、舂米（律令財政運用の基本単位である白米）、碾磑（水車で動かす臼）の事」と記されている。