Jeung-do (증도, 曾島) is an island in Shinan county, Jeollanam-do. It is perhaps best known for the annual mud festival held on its Ujeon Beach.
Jeung-do has an area of 28.16 kilometers and in 1999 had a population of 1,906. It is located 51 kilometers west of Mokpo, and is under the jurisdiction of Shinan's Jeungdo-myeon.