The museum won gold in the South West Tourism Awards
The Corinium Museum in Cirencester, Gloucestershire, has been accredited by a national scheme in recognition of the standard of its care and collections.
The award, from the Museums, Libraries and Archives Council (MLA), looks at how a venue is run and managed and the services it offers to visitors.
The Corinium Museum holds nationally important collections of archaeology, social history and old photographs.
In 2008 the museum won gold in the South West Tourism Excellence Awards.
Cotswolds District Councillor David Fowles said: "The museum service staff take a great deal of care in looking after our collections and providing opportunities for people to use, enjoy and learn from the collections we have on display.
"Well done to all the staff and volunteers for a top-class museum service for our visitors."