| Alastaro | |
| Official Name: | Finnish: Alastaron kunta Swedish: Alastaro kommun |
| Settlement Type: | Former municipality |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Name: | Finland |
| Subdivision Type1: | Region |
| Subdivision Name1: | Southwest Finland |
| Subdivision Type2: | Sub-region |
| Subdivision Name2: | Loimaa sub-region |
| Extinct Title: | Consolidated |
| Extinct Date: | 2009 |
| Area Footnotes: | [1] |
| Area Total Km2: | 258.12 |
| Area Land Km2: | 256.8 |
| Area Water Km2: | 1.32 |
| Population As Of: | 2008-12-31 |
| Population Footnotes: | [2] |
| Population Total: | 2910 |
| Population Density Km2: | auto |
| Blank1 Name: | Climate |
| Blank1 Info: | Dfc |
| Timezone: | EET |
| Utc Offset: | +2 |
| Timezone Dst: | EEST |
| Utc Offset Dst: | +3 |
| Coordinates: | 60.9542°N 22.8639°W |
Alastaro (in Finnish pronounced as /ˈɑlɑstɑro/) is a former municipality of Finland. It was merged into the town of Loimaa on 1 January 2009.
Alastaro is located in the province of Southern Finland and is part of the Southwest Finland region. The municipality had a population of 2,910 (31 December 2008) and covered an area of of which 1.32 km² is water. The population density was 11.33 inhabitants per km².
The municipality was unilingually Finnish.
The Alastaro Circuit opened in 1990.