Chief State Councillor under Sukjong; top graduate of the civil examination; pen name Mongeojeong

| Life | 1634 ~ 1709 |
| Era | 조선 후기 |
| Clan | 대구 서씨 |
Seo Mun-jung (1634-1709) was a late-Joseon civil official of the Daegu Seo clan. Courtesy name Doyun, pen name Mongeojeong, he served as Chief State Councillor under Sukjong. A grandson of Seo Gyeong-ju, he was a natural son of Seo Jeong-ri but was adopted into the line of Seo Gyeong-u as heir of Seo Won-ri. His mother was a daughter of Yi Si-bal of the Gyeongju Yi.
He topped the 1680 palace examination and became Magistrate of Gwangju, then served as governor of Gyeongsang, royal secretary and Vice Minister of Taxation, and by Sukjong's favor as Commander of the Royal Guards, Chief Royal Secretary and Vice Minister of Works. He was dismissed in the 1689 Gisa purge but returned after the 1694 Gapsul reversal as Magistrate of Gangneung, Governor of Hanseong, Minister of Military Affairs, Minister of Justice, Commander of the Military Training Command and Inspector-General.
He became Right State Councillor in 1698 and, after an embassy to China, Left State Councillor and then Chief State Councillor in 1699, later retiring as Pan-jungchubusa. In the preface to the Daegu Seo genealogy of 1702 he is said to have written that the Seo had originally branched from Icheon. His portrait and case are Treasure No. 1898.
His paternal grandparents were Seo Gyeong-ju and Princess Jeongsin, yet he was adopted by Seo Won-ri of the Seo Gyeong-u line.
Dismissed in the Gisa purge and restored after the Gapsul reversal, he served as minister and army commander and became Chief State Councillor in 1699. He is said to have been close to Seo Jong-tae too.
The location of his tomb was not confirmed here.
Sons include Seo Jong-bo and Seo Jong-ro. He continued the Seo Gyeong-u line as an adopted heir.