In 1350, his father Enshin died and his eldest brother Norisuke became the head of the family; and when Norisuke died in 1351, Norisuke (Sokuyu) became the head of the family.
1350年に父・円心が没し、長兄・範資が総領（当主）となるが、1351年に範資が急死、則祐が総領となる。