In 1337, when his father resigned from the Udaijin (minister of the right), Sanenatsu was promoted to a Sangi (royal advisor) and, within the same year, he was also promoted to Jusanmi (Junior Third Rank) and became a court noble.
1337年、父が右大臣を辞任すると参議に昇進し、その年のうちに従三位となって公卿に列した。