Later, although there were several instances of Naidaijin being placed for special reasons, it is thought that Naidaijin as a permanent official started with FUJIWARA no Michitaka in the middle Heian period.
以後、特殊の事情によって内大臣が設置される例が複数回あったが、常置の官としての内大臣は、平安時代中期の藤原道隆以後と考えられている。