The animal lashed out with its back feet as he approached it from behind to pat it on the backside after it had been let out onto the streets at the annual festival.
The 37-year-old, named locally as Jose Ramon Bronte Les, was left haemorrhaging blood and appeared to be virtually lifeless as he dropped to his knees. Reports in Spain said he survived.
One onlooker at the festival in Pinoso, near Alicante, captured the dramatic moment on video, showing that the man had to be dragged to safety with blood gushing down his leg after being gored.
Incredible video footage shows how the bare-chested man was trampled and pinned down for almost half a minute by the incensed animal, its horns missing his head and stomach by mere inches