Kevin Hehir, 48, was astonished when he spotted the fox while out walking.
The black fox is so rare that wildlife experts believe there are only a handful of the breed left in the country.
In medieval times, the black fox was considered a bad omen by superstitious villagers.
Mr Hehir, from Preston, Lancashire, was walking in a cemetery with a friend, when he spotted the animal among the gravestones.
"It was on the outskirts of Chorley, I don't want to give the exact location out as it's a very rare fox and I don't want people to go and try and catch it," he said.
"We were walking along looking at gravestones and I spotted it. I thought: "It's a myth, there's no such thing".
The black fox is in fact a red fox which is going through a phase where the colour of its fur is particularly dark.
The unusual colouring is normally seen on growing cubs before the fox develops its dark chestnut coat, however some red foxes remain black due to a rare genetic flaw, which dates back hundreds of years.