| Jurisdiction: | Diocese |
| Saitama | |
| Local: | Japanese: カトリックさいたま教区 |
| Latin: | Dioecesis Saitamaensis |
| Country: | Japan |
| Territory: | Saitama, Tochigi, Gunma, and Ibaraki |
| Metropolitan: | Tokyo |
| Province: | Tokyo |
| Rite: | Latin Rite |
| Cathedral: | Cathedral of St Theresa of the Child Jesus in Urawa, Saitama |
| Area Km2: | 22,604 |
| Population: | 14,074,691 |
| Population As Of: | 2020 |
| Catholics: | 119,820 |
| Catholics Percent: | 0.9 |
| Bishop: | Mario Michiaki Yamanouchi[1] |
| Metro Archbishop: | Tarcisio Isao Kikuchi |
| Emeritus Bishops: | Marcellino Taiji Tani Bishop Emeritus (2000-2013) |
| Map: | Giappone - Diocesi di Saitama.png |
| Website: | Website of the Diocese |
The Roman Catholic Diocese of Saitama (Latin: Dioecesis Saitamaensis, Japanese: カトリックさいたま教区) is a Latin Church diocese of the Catholic Church located in the city of Saitama in the ecclesiastical province of Tokyo in Japan.