Period of Three States
The name changed from Ochahyeon in Baekje to Oa during the reign of King Gyeongdeok of Silla after the unification of three nations.
Goryeo Dynasty
- The name was changed to Jeongan in the early years of Goryeo Dynasty. During the reign of King Injong, it was changed to Jangheung and promoted to Bu with the name, Jeongju Gwansan.
- It was promoted to Hoejumok in 6th year of reign of King Wonjong.
- In 2nd year of reign of King Chungseon (1310), it was demoted again to Jangheungbu. During this time, due to the Japanese invasion, all residents moved to northern mountainous areas.
Joseon Dynasty
- In the first year of King Taejo (1392), a castle was built in Jungryeongsan Mountain in Suryeong district for a ruling place.
- In the 13th year (1413), Dohobu was transferred to Suryeong district in the following year.
- During the reign of King Sejo (1457), A camp was placed to govern two districts of Gangjin and Haenam
- In the 32nd year of King Seonjo (1599), the barracks were transferred from Gangjin to Jangheung.
- In the 37th year of King Seonjo (1604), it was moved to Gangjin old barrack.
- In the 9th year of King Hyeonjong (1699), a front barrack was established.
- In the 9th year of King Sukjong (1683), a barrack was transferred to Suncheon.
- In the 32nd year of King Gojong (1895), it was named Jangheung-gun.
After Modern Era
- In 1914, three myeons including Cheonpo, Hoeryeong and Ungchi were included in Boseong-gun which was restructured to 11 administrative districts.
- In November 1, 1936, through the merger of myeons, Budong-myeon became Jangheung-myeon, Namha and Namsang were merged into Yongsan-myeon, and Habal, Goma, Jukcheong of Namha-myeon and Goeup-myeon were merged into Gwansan-myeon, which became total 9 myeons.
- In November, 1940, Jangheung-myeon was promoted to Jangheung-eup with 1 eup, 18 myeons and 275 ri's.
- In July 1, 1972, With the adjustment of administrative district, Jangdong-myeon Gwangpyeong-ri was adjusted to Jangpyeong-myeon.
- In January 1, 1980, Jangheung-eup Geonsan 3-gu, Yeyang-ri and Daedeok-myeon Hoejin-ri were divided into 279 ri's.
- In December 1, 1980, Gwansan-myeon and Daedeok-myeon were promoted to Gwansan-eup and Daedeok-eup respectively with 3 eup's and 6 myeon's.
- In January 1, 1982, Jangheung-eup Geonsan 4-gu, Wondo-ri, Daedeok-eup Hoejin-ri, and Anyang-myeon Sumun-ri were divided into 3 eup's, 6 myeon's and 283 ri's.
- In October 19, 1985, Daedeok-eup Hoejin local office was established.
- In April 10, 1986, Hoejin-myeon was separated from Daedeok-eup into 3 eup's and 7 myeon's.
- In July 15, 1986, Gwansan-eup Okdang, Yongsan-myeon Inam, Punggil-ri, Anyang-myeon Haechang 3-gu, Jangdong-myeon Bukgyo 1-gu, Jangpyeong-myeon Yonggang 2-gu, Bongrim-ri, Usan-ri, Cheongyong-ri and Hoejin-myeon Jinmok 2-gu were divided into administrative districts of 3 eup's, 7 myeon's and 293 ri's.
- In December 31, 2001, Yuchi-myeon Wondeung-ri was established into administrative districts of 3 eup's, 7 myeon's and 294 ri's.
- In September 16, 2002, Jangheung-eup Haengwon 2-gu was separated into administrative districts of 3 eup's, 7 myeon's and 295 ri's until now.