The unidentified man was attempting to move another boulder, with four other men, that fell to the road from Mount Elden when his legs and pelvis were pinned, Coconino County Sheriff's office spokesman Gerry Blair said.
An ambulance and fire truck were unable to get to the location because of poor road conditions, but rescuers used a four-wheel-drive vehicle to reach the victim, KPHO-TV, Phoenix, reported. He was then driven out of the area and taken to a waiting ambulance.
There was no report of his condition at the hospital.
The men were on their way up the mountain to repair radio towers, Blair said.