| Ernstbach | |
| Mouth Location: | Wisper |
| Mouth Coordinates: | 50.0885°N 7.903°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Germany |
| Subdivision Type2: | State |
| Subdivision Name2: | Hesse |
| Length Km: | 12.5 |
| Basin Size Km2: | 35.3 |
Ernstbach is a 12.5km (07.8miles)-long river of Hesse, Germany. It is a left tributary of the Wisper River in the Taunus mountains, part of the Rhine River system.