The large black bear pounced on the unsuspecting climber as the man descended from the summit of Mount Futago in Japan. Taken totally by surprise at the ferocity of the attack the climber was caught in deadly scrap with the rampaging bear.
He managed to capture the attack using a helmet cam and later uploaded the footage online.
The now-viral video shows the climber yelling and screaming at the bear as it suddenly launches at him from among the rocks.
Commenting on the video, the climber describes punching and kicking the bear as he struggled to fend off the large beast.
Looking back the man believes he may have accidentally provoked the bear by getting to close to nearby cubs.
The climber wrote beside the video: “I was attacked by a bear from behind while descending the rocky ridge of Mt.Futago in Chichibu City, Saitama Prefecture, Japan.
“Instead of fear, I switched to the feeling that if it was coming, I had no choice but to face it.
“I invaded bear territory, but since they attacked me, I defended myself with self-defense.”
He went on to describe using martial arts moves he learnt as a kid to fight off the animal.
Remarkably the climber managed to survive the ordeal with no major injuries.
He said: “My hands were scratched and cut from desperately holding on to the rock.
“My right wrist was slightly sprained after hammering the rock and the bear.”