KOSE no Maro was appointed to Jushiinoge (Junior Fourth Rank, Lower Grade) Minbukyo (Minister of Popular Affairs) during the reign of Emperor Mommu (on April 22, 705 on the old calendar), and to Sadaiben (major controller of the left) during the reign of Empress Genmei (March 13, 708 on the old calendar).
文武天皇の御世に従四位下民部卿（慶雲2年4月22日(旧暦)）、に任じられ、元明天皇の御世となり左大弁に任じられる（和銅元年3月13日(旧暦)）。