Tadahira was a kuge (Japanese noble) who is credited with writing and publishing Engishiki. He is one of the principle editors responsible for the development of the Japanese legal code known as
Sandai-kyaku-shiki, sometimes referred to as the Rules and Regulations of the Three Generations.
Tadahira served as regent under Emperor Suzaku who ruled from 930 to 946.
- September 17, 914 (Engi 14, 25th day of the 8th month): Dainagon Tadahira was named udaijin.
- October 16, 930 (Enchō 8, 22nd day of the 9th month): Tadahira was appointed sesshō.
- September 7, 936 (Jōhei 6, 19th day of the 8th month): He assumed the role of daijō-daijin.
- February 16, 937 (Jōhei 7, 4th day of the 1st month): He presided over the coming of age ceremony of Emperor Suzaku.
- November 29, 941 (Tengyō 4, 8th day of the 11th month): He became kampaku.