| Jurisdiction: | Diocese |
| Hamhung | |
| Latin: | Dioecesis Hameungensis |
| Local: | 함흥 교구 |
| Metropolitan: | Seoul |
| Province: | Seoul |
| Area Km2: | 49,375 |
| Catholics: | unknown |
| Denomination: | Roman Catholic |
| Rite: | Roman Rite |
| Established: | August 5, 1920 |
| Cathedral: | Destroyed in Korean War |
| Bishop: | Sede vacante |
| Metro Archbishop: | Andrew Yeom Soo-jung |
| Apostolic Admin: | Simon Kim Ju-young |
| Map: | Diocese of Hamhung.svg |
The Roman Catholic Diocese of Hamhung is a diocese of the Latin Church of the Roman Catholic Church in North Korea.
Originally erected as the Apostolic Vicariate of Wonsan in 1920, the name has been changed twice, once to Kankoensis o Hameungensis in 1940, and finally, as the Apostolic Vicariate of Hamhung in 1950. Like the Diocese of Pyongyang, the Vicariate was elevated to a full diocese in 1962. The diocese is a suffragan of the Archdiocese of Seoul.
In 1949, 166 priests and religious were martyred in the Communist revolution of Kim Il Sung. This left the diocese bereft of priests. Bishop Boniface Sauer, the abbot of Tokwon Abbey, had died in 1950, and no bishop had been re-appointed to the diocese. Finally, in 1962, Timotheus (Franz Xaver) Bitterli, was appointed in absentia as the bishop of the diocese, and was the apostolic administrator for 20 years until his resignation in 1981. Since then, the diocese has remained vacant, and it will likely remain so as long as the persecution of Christians in North Korea continues.