| Dema Union | |
| Native Name: | ডেমা ইউনিয়ন |
| Settlement Type: | Union |
| Pushpin Map: | Bangladesh |
| Pushpin Map Alt: | Location in Bangladesh |
| Pushpin Label Position: | Right |
| Subdivision Type: | Country |
| Subdivision Name: | Bangladesh |
| Subdivision Type1: | Division |
| Subdivision Name1: | Khulna |
| Subdivision Type2: | District |
| Subdivision Name2: | Bagerhat |
| Subdivision Type3: | Upazila |
| Subdivision Name3: | Bagerhat Sadar |
| Established Title: | Established |
| Established Date: | 1961 |
| Unit Pref: | Metric |
| Area Total Km2: | 44.21 |
| Population As Of: | 2011 |
| Population Total: | 24,745 |
| Population Density Km2: | auto |
| Timezone1: | BST |
| Utc Offset1: | +6 |
| Official Name: | Dema Union |
Dema Union (Bengali: ডেমা ইউনিয়ন) is a Union Parishad under Bagerhat Sadar Upazila of Bagerhat District in Khulna Division, Bangladesh.[1] It has an area of 44.21 km2 (17.07 sq mi) and a population of 24,745.[2]