His grandfather was KOSE no Tokuta, who was Daishu (the third grade of nineteen grades of cap rank, which corresponds to Shonii, Senior Second Rank of Taiho Ritsuryo, Taiho Code) and Sadaijin (minister of the left) of the Naniwa Court and his father was KOSE no Kuromaro, who was Chunagon (Middle councilor) and Shokin (which corresponds to Shogoinojo and Shogoinoge, Senior Fifth Rank, Upper and Lower Grades and Jugoinojo and Jugoinoge, Junior Fifth Rank, Upper and Lower Grades of Taiho Ritsuryo, Taiho Code).
祖父は難波朝左大臣大繍巨勢徳多、父は中納言小錦中巨勢黒麻呂。