The suspect approached the counter with two packets of crisps but then asked the shop assistant to give him the money from the till.
Having been handed the money, the suspect left in what is believed to be a dark blue Rover 25 in the direction of the Cocked Hat roundabout. The car had twin headlights and a silver surround to the front grille.
The suspect is described as a:
- White man
- 45 to 55 years-old
- Medium to heavy build
- 5ft 7 to 6ft tall
- Dark brown hair which is receding at the crown and thinning on top.
- Wearing a dark blue jumper with a similar coloured collared shirt underneath, stone coloured trousers and sand coloured shoes.
PC Mark Brenson from Gosport police station said: "I would appeal to anyone who can identify the man in the CCTV to contact the police as we would like to speak to him in connection with this offence.
"Crimes like this are thankfully rare but the young girl who was working in the shop at the time was extremely frightened and upset by this incident and the theft will have a significant impact on the small business targeted."
Anyone with information is asked to contact PC Brenson at Gosport police station on 101 or call the Crimestoppers charity anonymously on 0800 555 111.