Sejo of Joseon

Sejo of Joseon (Korean: 조선 세조, 2 November 1417 – 23 September 1468, r. 1455–1468) was the seventh king of the Joseon Dynasty of Korea. He was the son of King Sejong and brother of Munjong of Joseon and uncle of Danjong of Joseon, against whom he led a coup d'état to become king himself in 1455.

세조 어진 초본.jpg
King of Joseon
Reign11 June 1455 – 23 September 1468
PredecessorDanjong of Joseon
SuccessorYejong of Joseon
Born2 November 1417
Died23 September 1468(1468-09-23) (aged 50)
ConsortQueen Jeonghui
Posthumous name
King Hyejang Sungcheon Chedo Yeolmun Yeongmu Jideok Yunggong Seongsin Myeongye Heumsuk Inhyo the Great
Temple name
Sejo (세조, 世祖)
HouseJeonju Yi
FatherSejong the Great
MotherQueen Soheon
Korean name
Revised RomanizationSejo
Birth name
Revised RomanizationLi Yu
McCune–ReischauerLi Yu
Courtesy name
Revised RomanizationSuji


Early lifeEdit

Born in 1417 as Yi Yu, King Sejong the Great's second son, he showed great ability at archery, horse riding and martial arts. He was also a brilliant military commander, though he never went to the battlefront himself. He became Grand Prince Suyang (수양대군, 首陽大君) in 1428, the name by which he was better known.

Following King Sejong's death, Suyang's ill brother, Munjong, took the throne but soon died. The crown passed to his 12-year-old son, Danjong. The new emperor was too young to rule the nation, and all political processes were controlled by then-premier Hwangbo In and General Kim Jongseo, who was vice-premier. As Kim Jongseo and his faction used the chance to extend the power of court officials against many royal family members, the tension between Kim and Suyang greatly increased; not only Suyang himself, but his younger brother, Grand Prince Anpyeong, also sought an opportunity to take control of the kingdom.

Suyang surrounded himself with trusted allies, including his famous adviser, Han Myung-hoi. Han advised Suyang to take over the government in a coup, and on 10 November (10th day of the 10th lunar month) 1453, he killed Kim Jongseo and his faction, thereby taking the reins of power into his own hands. After the coup he arrested his own brother, Anpyeong, first sending him into exile, then sentencing him to death.


Finally in 1455 he forced his powerless young nephew, Danjong, to abdicate, declaring himself seventh king of the Joseon dynasty. Later he demoted Danjong to prince and ordered him to be poisoned after his younger brother, Grand Prince Geumsung, and later six scholars including Seong Sam-mun, Pak Paeng-nyeon, and Yi Gae plotted to remove Suyang from power in an attempt to put Danjong back on the throne.

Despite having snatched the throne from his young nephew and killing many people in the process, he proved himself one of the most able rulers and administrators in Korean history. First, he strengthened the monarchy established by King Taejong by weakening the power of the prime minister and bringing staff directly under the king's control. He also strengthened the administrative system, which had also been introduced by Taejong, enabling the government to determine exact population numbers and to mobilize troops effectively. Just like Taejong, he was a hardliner with regards to foreign policy and attacked the Jurchens on the northern front in 1460 (오랑캐/兀良哈) and 1467 (호리개/胡里改). He also revised the land ordinance to improve the national economy. He executed scholars from King Sejong's era for plotting against him, but encouraged publication of history, economics, agricultural, and religious books.

Last yearsEdit

Most importantly, he compiled the Grand Code for State Administration, which became the cornerstone of dynastic administration and provided the first form of constitutional law in a written form in Korea. He died in 1468, and the throne passed to his sickly son, Yejong.


  1. Queen Jeonghui of the Papyeong Yun clan (8 December 1418 – 6 May 1483) (정희왕후 윤씨)[1][2]
    1. Yi Jang, Crown Prince Uigyeong (1438 – 2 September 1457) (이장 의경세자)[3]
    2. Princess Uisuk (1442 – 3 December 1477) (의숙공주)[4]
    3. Yi Hwang, Grand Prince Haeyang (14 January 1450 – 31 December 1469) (이황 해양대군)
    4. Yi Se-Hui (이세희) or Princess Uiryeong (의령공주) or Princess Uihwa (의화공주)[5][6]
  2. Royal Noble Consort Geun of the Seonsan Park clan (1425 – ?) (근빈 박씨)[7][8]
    1. Yi Seo, Prince Deokwon (6 March 1449 – 22 July 1498) (이서 덕원군)
    2. Yi Seong, Prince Changwon (1458 – 1484) (이성 창원군)
  3. Deposed Consort So-yong of the Park clan (폐 소용 박씨)
    1. Unnamed son (Died in childhood)
  4. Consort Suk-won of the Goryeong Shin clan (숙원 신씨)

Books compiled by SejoEdit

Sejo of Joseon compiled a number of books based on his interests. One includes Seokbosangjeol, a biography of Gautama Buddha.[9] He also created two other books:

  • Wolin sukbo (월인석보, 月印釋譜)
  • Yukdae byungyo (역대병요, 歷代兵要)

His full posthumous nameEdit

  • King Sejo Hyejang Sungcheon Chedo Yeolmun Yeongmu Jideok Yunggong Seongsin Myeongye Heumsuk Inhyo the Great of Korea
  • 세조혜장승천체도열문영무지덕융공성신명예흠숙인효대왕
  • 世祖惠莊承天體道烈文英武至德隆功聖神明睿欽肅仁孝大王

Depiction in arts and mediaEdit

See alsoEdit


  1. ^ Daughter of Yun Beon (윤번), Lord Jeongjeong (정정공), Internal Prince Papyeong (파평부원군); and Lady Heungnyeong, Princess Consort to the Internal Prince, of the Incheon Lee clan (흥녕부대부인 이씨)
  2. ^ Married in 1428, originally as Sejo's Princess Consort
  3. ^ He was first known as Prince Dowon (도원군) when his father was still Grand Prince
  4. ^ Later married Jeong Hyeon-jo (정현조), son of Jeong In-ji (정인지), Lord Munseong (문성공), and later Chief State Councillor (영의정, 11 June 1455); created Prince Consort Haseong (하성군)
  5. ^ From the unofficial history (야사 野史), accurately from the "Geumgye Pildam" (금계필담 錦溪筆談; by Seo Yoo-yeong (서유영) in 1873), but unable to confirm from the official Annals. But in 1446 (Sejong's 28th year), the Annals recorded Grand Prince Suyang (as he was still known that time) as having "1 son & 2 daughters", but there is no record or possibility of her having existed
  6. ^ The name recorded down in said unofficial history
  7. ^ Originally of Gwi-in (귀인) rank (along with her title "Palace of Motherly Kindness and of Long Life" (자수궁 慈壽宮)), was elevated to Bin rank on 15 June 1483 (along with her title "Palace of Propriety and of Long Life" (창수궁 昌壽宮))
  8. ^ Elder sister of Park Paeng-nyeon (박팽년) (later one of the Six Martyred Ministers)
  9. ^ "Life History and Sermon of Buddha Abstracted from Buddhist Scriptures". World Digital Library. 1447. Retrieved 24 May 2013.
Sejo of Joseon
Born: 1417 Died: 1468
Regnal titles
Preceded by
King of Joseon
11 June 1455 – 23 September 1468
Succeeded by