| Type: | cadastral |
| Derby | |
| State: | sa |
| Est: | 1877[1] |
| Area: | 3844 |
| Coordinates: | -31.74°N 139.49°W |
| Lga: | Pastoral Unincorporated Area[2] |
| Region: | Far North[3] |
| Near-Nw: | Taunton |
| Near-S: | Lytton |
| Near-Sw: | Granville |
| Near-W: | Hanson |
The County of Derby is one of the 49 counties of South Australia. It was proclaimed 1877 by Governor Anthony Musgrave.[2] It covers a rectangular portion of unincorporated pastoral land in the state's Far North. The west of the county includes some of the eastern foothills of the Flinders Ranges and the county's northern border is about south of Lake Frome.[2] As of 2014, the county has not been divided into hundreds.[1]