The robbery took place at 10pm on Tuesday when cash, cigarettes and alcohol stolen by two men.
Staff at the store were threatened by the men in the traumatic ordeal, but no injuries were sustained.
A spokesperson for West Midlands Police said: "We are investigating an armed robbery at a shop on Turner Lane, Brierley Hill at 10pm on Tuesday evening (20 September).
"Two men armed with a hammer and screwdriver climbed over the counter and stole cash, cigarettes and alcohol.
"Staff members were threatened, but fortunately were not injured in this traumatic ordeal.
"Anyone with information can contact us via Live Chat on our website or by calling 101. Please quote crime ref 20/820780/22."