Son of Yi Gwi and merit subject of the Injo Restoration who served as Minister of Works and Punishments (pen name Seobong; posthumous title Chungjeong)

| Life | 1594 ~ 1660 |
| Era | 조선 중기 |
| Clan | 연안 이씨 |
Yi Si-bang (1594-1660) was a Joseon civil official of the Yeonan clan, with courtesy name Gyemyeong, pen name Seobong and posthumous title Chungjeong. His father was Yi Gwi, his mother a daughter of Jang Min of Indong, and his elder brother Yi Si-baek became Chief State Councillor. He took part in the Injo Restoration as a second-class merit subject and Prince of Yeonseong, and in suppressing Yi Gwal's rebellion.
He began as magistrate of Seosan in 1625 and served as magistrate of Gwangju, vice mayor of Hanseong, magistrate of Naju and governor of Jeolla. During the 1627 invasion he inspected Ganghwa's defenses and managed grain for the eight provinces, and he is credited with building Ibamsan Fortress. In 1640, after exile, he was made magistrate of Jeju, where he is said to have protected the deposed Gwanghae and handled the burial rites in 1641.
Implicated in the 1644 Sim Gi-won affair he was dismissed, but returned the next year and became Minister of Works in 1648. He oversaw royal funerals including Injo's tomb, served as Mayor of Hanseong under Hyojong, and urged adoption of the Daedongbeop in Jeolla and Chungcheong. He died in 1660 during repairs of Namhansanseong, was posthumously named Chief State Councillor, and his portrait in official dress is Treasure No. 1482.
As Jeolla governor in 1637 he stressed grain supply and built Ibamsan Fortress; appointed magistrate of Jeju in 1640, he is said to have protected the deposed Gwanghae there.
The full-length portrait in official dress, part of the Yi Si-bang portraits, is Treasure No. 1482, and the set is Daejeon Tangible Cultural Heritage No. 38.
The tomb was not confirmed here. His spirit-way stele in Boryeong is Boryeong City Local Heritage No. 9.
Details of descendants were not confirmed. The set of Yi Si-bang portraits is Daejeon Tangible Cultural Heritage No. 38.