| Municipality of Demir Hisar | |
| Native Name: | Општина Демир Хисар |
| Native Name Lang: | mk |
| Settlement Type: | Municipality |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Name1: | Pelagonia |
| Seat Type: | Municipal seat |
| Seat: | Demir Hisar |
| Leader Title: | Mayor |
| Leader Name: | Nikola Najdovski (VMRO-DPMNE)[1] |
| Area Total Km2: | 480.13 |
| Population Total: | 7260 |
| Population Density Km2: | auto |
| Area Code: | 47 |
| Blank Name Sec1: | car plates |
| Blank Info Sec1: | DH |
| Timezone: | CET |
| Utc Offset: | +1 |
Demir Hisar (Macedonian: Демир Хисар in Macedonian pronounced as /dɛˈmir‿xisar/) is a municipality in the southwestern part of North Macedonia. Demir Hisar, which means "iron fortress" in Turkish, is also the name of the town where the municipal seat is located. The Demir Hisar Municipality is part of the Pelagonia Statistical Region.
The municipality borders the Kičevo Municipality to the north, the Kruševo and Mogila Municipalities to the east, the Bitola Municipality to the south, and the Resen, Ohrid, and Debarca Municipalities to the west.
According to the last national census from 2021, this municipality has 7,260 inhabitants.
Ethnic groups in the municipality include:
| 2002 | 2021 | |||
| Number | % | Number | % | |
| TOTAL | 9,497 | 100 | 7,260 | 100 |
| Macedonians | 9,179 | 96.7 | 6,708 | 92.4 |
| Persons for whom data are taken from administrative sources | n/a | n/a | 269 | 3.71 |
| Albanians | 232 | 2.4 | 218 | 3.0 |
| Turks | 35 | 0.4 | 4 | 0.06 |
| others | 51 | 0.5 | 61 | 0.84 |