Daijō-daijin

Pre-modern Japan
Part of a series on the politics and government of Japan during the Nara and Heian periods
Daijō-kan (Council of State)
Chancellor / Chief Minister	Daijō-daijin
Minister of the Left	Sadaijin
Minister of the Right	Udaijin
Minister of the Center	Naidaijin
Major Counselor	Dainagon
Middle Counselor	Chūnagon
Minor Counselor	Shōnagon
Eight Ministries
Center	Nakatsukasa-shō
Ceremonial	Shikibu-shō
Civil Administration	Jibu-shō
Popular Affairs	Minbu-shō
Military	Hyōbu-shō
Justice	Gyōbu-shō
Treasury	Ōkura-shō
Imperial Household	Kunai-shō

The Daijō-daijin or Dajō-daijin(太政大臣^?, Chancellor of the Realm) was the head of the Daijō-kan (Department of State) in Heian Japan and briefly under the Meiji Constitution.

Emperor Tenji's favorite son, Prince Ōtomo, was the first to have been accorded the title of Daijō-daijin during the reign of his father. The Asuka Kiyomihara Code of 689 marks the initial appearance of the Daijō Daijin in the context of a central administrative body composed of the three ministers: the Daijō Daijin (Chancellor), the Sadaijin (Minister of the Left), and the Udaijin (Minister of the Right). These positions were consolidated under the Code of Taihō in 702.

As the Fujiwara clan—which dominated the regency—gained influence, the official government offices diminished in power. By the 10th century, chancellors had no power to speak of unless they were simultaneously regent, or otherwise supported by the Fujiwara. Although the position continued in name until 1885, by the beginning of the 12th century, the office was essentially powerless, and was often vacant for lengthy periods. Substantial administrative power over the government was in other hands.

This prominent office was briefly resurrected under the Meiji Constitution with the appointment of Sanjō Sanetomi in 1871, before being abolished completely in 1885 in favour of the newly created office of Prime Minister of Japan.