Alphamstone is a village and civil parish in Essex, England. It is located south of Sudbury, Suffolk and is northeast from the county town of Chelmsford. The village is in the district of Braintree and in the parliamentary constituency of Saffron Walden. The parish is part of the Stour Valley South parish cluster.
The village is very close (about ) to the River Stour, which forms the Essex/Suffolk border in the local area.