The ‘Rammer’ was taken from a mini digger parked on a bridge on the U257A road at Westerkirk sometime between last Friday and Monday.
It was in new condition.
Constable Callum Ruddick, of Police Scotland at Langholm, said: “This piece of equipment would have needed a few people to move and would have required a knowledge of how to operate the digger as the hammer itself was attached to the boom.
“We are keen to hear from anyone who may have seen anyone near the digger over the weekend when the works were closed. Callers can contact us through 101.”