Chihuahua state prosecutors read the charges against Francisco Velazquez Samaniego during a hearing in which they also listed the names and injuries of the people killed.
"He didn't meet the age and health requirements needed to be part of the show," prosecutor Gerardo Carbajal said. He didn't say what those requirements are.
Velazquez Samaniego, 51, appeared before a judge wearing a neck brace as another person died at a hospital, raising the death toll from Saturday's incident to nine. At least 80 people were hurt during the monster truck exhibition in the northern city of Chihuahua.
Velazquez Samaniego said in court that his helmet came off as the truck bounced over old cars and he lost consciousness when his head hit metal bars inside the cabin.
"I was driving to one side and then I turned around and drove to the other side, my helmet came off and I hit my head and lost consciousness," he said. "I wasn't conscious when the truck fell" on the people.
Organizers of the event have said hundreds of people gathered without permission in the pit area of a makeshift arena in a park.
Veteran monster truck show organizers said spectators should never have been standing that close to the arena floor unprotected, regardless of the trajectory of the truck.
Authorities have made no other arrests in the case.