| Jurisdiction: | Diocese |
| Castanhal | |
| Latin: | Dioecesis Castagnalensis de Pará |
| Local: | Diocese de Castanhal |
| Country: |  Brazil |
| Metropolitan: | Belém do Pará |
| Rite: | Latin Rite |
| Established: | 29 December 2004 (years ago) |
| Cathedral: | Cathedral of Mary Mother of God in Castanhal, Pará |
| Area Km2: | 14,338 |
| Population: | 722,104 |
| Population As Of: | 2006 |
| Catholics: | 580,400 |
| Catholics Percent: | 80.4 |
| Metro Archbishop: | Alberto Taveira Corrêa |
| Website: | Blog of the Diocese |
The Roman Catholic Diocese of Castanhal (la|Dioecesis Castagnalensis de Pará) is a diocese located in the city of Castanhal in the ecclesiastical province of Belém do Pará in Brazil.