The incident occurred between midnight and 12.30am on Friday, April 4 on King George Road.
The suspect sat inside a red Ford Ranger when he was spotted by friends of the car owner.
They called out the owner and the man then ran off with a bag of ratchet straps taken from the vehicle.
The suspect is described as:
25 to 30-years-old
Wearing a black winter hat, dark coloured fleece and black trousers.
Did you see a man running from the direction of King George Road or anyone in the area matching the description of the suspect?
If so please contact Police Staff Investigator Rebecca Quirk at Andover police station by calling 101.
Please also remember to remove personal items from your vehicle when it is left unattended and lock it at all times.