Two masked men entered the post office in Ballinhassig yesterday evening just before 4pm and demanded money.
One of the men was armed with a shotgun and the other man had a machette.
No one was injured during the robbery and the men then fled the scene in a grey Citroen C3 car, which Gardaí believe was being driven by a third man.
The men were seen fleeing in the direction of Spur Hill/Liberty Hill. The car was later found on fire in a field near Spur Hill.
Gardaí are asking anyone who witnessed the incident or was in the Spur Hill area yesterday between 3:45 and 4:30pm to contact them in Bandon on 023 885 22 00
They are also asking anyone with dash cam footage of the area to come forward.
