| Altmünster | |
| Native Name: | Oidmünsta |
| Pushpin Map: | Austria |
| Pushpin Mapsize: | 270 |
| Pushpin Map Caption: | Location within Austria |
| Coordinates: | 47.9014°N 13.7514°W |
| Subdivision Type: | Country |
| Subdivision Name: | Austria |
| Subdivision Type1: | State |
| Subdivision Name1: | Upper Austria |
| Subdivision Type2: | District |
| Subdivision Name2: | Gmunden |
| Parts Style: | para |
| Leader Title: | Mayor |
| Leader Name: | Martin Pelzer |
| Elevation M: | 442 |
| Population Density Km2: | auto |
| Timezone: | CET |
| Timezone Dst: | CEST |
| Utc Offset: | +1 |
| Utc Offset Dst: | +2 |
| Registration Plate: | GM |
| Postal Code Type: | Postal code |
| Postal Code: | 4813 |
| Area Code Type: | Area code |
| Area Code: | 07612 |
| Website: | www.altmuenster.at |
Altmünster (Central Bavarian: Oidmünsta), also known as Altmünster am Traunsee, is a market town located about 3 kilometres south of Gmunden in the Austrian state of Upper Austria, on the west shore of the Traunsee. Its economic base consists primarily of tourism, light industry, and as a bedroom community for people working in larger communities such as Gmunden and Vöcklabruck.
See also: List of twin towns and sister cities in Austria.
Altmünster is twinned with:
Hoegaarden, Belgium