Two hooded robbers threatened a man with a knife before stealing a large amount of business takings.
It happened at around 12.30am on Sunday morning when the victim, a 42-year-old man, was approached by two men on Halifax Road in Batley.
One of the men threatened the victim with a knife before both made off with a large amount of cash in a white bag.
The suspects made off in a vehicle on Common Road.
The money stolen was the takings from a local business.
The victim was not injured during the incident.
The suspects are described as white men, of slim build and wearing dark clothing with hoods up.
Anyone who may have been in the area and seen or heard anything suspicious, or who may have any information is asked to contact Kirklees District CID via 101 quoting 13170465727.
Information can also be passed anonymously to the independent crime fighting charity Crimestoppers on 0800 555 111.