A man wearing a balaclava threatened a member of staff at a South Normanton supermarket with a knife before making off with cash from the till.
The incident took place at 7.10am on Saturday, January 31, at Manor Supersave in the Market Place.
The man took a bottle of water to the till before demanding money.
A spokesman for Derbyshire Police, said: “The man went in the store and took a bottle of water to the till. He produced a knife and threatened a member of staff, asking for money.
“When the till was open he helped himself to cash. He then ran off towards Ball hill.”
The robber is described as white, 5ft 10ins, aged between 19 and 20, wearing black jogging bottoms, black Nike trainers, a light grey top with a darker grey hooded top over the top. He had the hood pulled up and was wearing a black balaclava.
Anyone with information should call Derbyshire Police on 101.