| Hangul: | 서재창 |
| Hanja: | 徐載昌 |
| Rr: | Seo Jae-chang |
| Mr: | Sŏ Chae-ch'ang |
Seo Jae-chang (; 29 October 1866 – 13 December 1884) was a Korean politician, serviceperson, liberal ideologist during the Joseon period. He was a member of the reformist Party(개화당;開化黨). In 1884 he was a participant in the Gapsin coup.[1] The coup failed and he was arrested and executed.[1] Seo was the younger brother of Seo Jae-pil.
Jae-chang was born 1866 (Daegu Seo Clan) in Bosong in South Jeolla Province. He was the fourth son of Seo Gwang-ho, governor of Dongbok County and Lady Lee of Seongju. His elder brothers were Jae-chun, Jae-hyung and Jae-pil and his younger brother was Jae-wu. He had two sisters.
He studied in Japan, recommended by Yu Dae-chi and Lee Dong-in. Jae-chang studied sericulture and military science. Later he returned to his country.
In 1884 he adopted a distant relation Seo Sang-wu's adopted son. In January to July, 1884, he returned to Japan. He entered a Toyama military school with Jae-pil, but in July he went to Seoul to plan a revolt with Kim Ok-kyun, Park Yeong-hyo and other members of Reformist Partys, Hong Yeong-sik, Park Yeong-kyo, Yun Chi-ho, Yun Ung-ryeol, Jae-pil and his father's fifth cousin Soh Kwang-pom.
In October, they undertook the Gapsin coup in Seoul. Queen Min mobilized Qing dynasty forces, who killed Hong Young-sik and Park Yeong-kyo in battle. The coup failed.
In October 21, Jae-chang escaped, but was seized by the Chinese. He was sent to Seoul prison of Uikeumbu. On December 13, he was executed by firing squad, Gungigam in Seoul. His family was arrested and to imprisonment, with some committing suicide. Only Jae-pil escaped on a Japanese boat to exile in Tokyo.