A staff member was taped to a rail by a man wielding a knife during a raid on a Frankie and Benny's restaurant in Gloucester on Sunday.
Police have issued an appeal for information after the armed thief entered the restaurant's office and demanded cash at 11.15pm.
The staff member, who had been cashing up, handed over the money, but the thief proceeded to tape him to a rail next to a fire exit before making off with the cash in a black, drawstring JD bag.
The offender is described as a white man, 6ft tall, of stocky build and wearing a black hoodie, black tracksuit trousers, a black hat and a scarf over his face.
He made off in the direction of Mercia Road.
Police would like to hear from anyone who witnessed any suspicious activity in the area or has any information which could help their enquiries.
Anyone with information is asked to call 101 quoting incident 403 of 4 November.