In 989, in spite of Emperor Enyu's objection, Kaneie appointed his eldest son Michitaka Nai-daijin (Minister of the Center) to realize the first '4-minister system' in the history of Ritsuryo code-based politics, and after Yoritada died in the same year, Kaneie appointed himself Dajo-daijin to take over his post.
永祚(日本)元年（989年）、円融法皇の反対を押し切って長男・道隆を内大臣に任命して、律令制史上初めての「大臣4人制」を実現させ、更にこの年に頼忠が死去すると、その後任の太政大臣に就任した。