The union is angry at imminent tests of driver-free Tube trains on the Jubilee line, which it argues could lead to unstaffed stations and ticket offices.
“Every train must have a driver, to ensure the safe and effective running of the Underground,” said the RMT general secretary Bob Crow.
“Plans to scrap drivers or reduce their driving duties are risking safety, services and jobs and are motivated by saving money and undermining trade unionism.”
Mayor of London Boris Johnson said during his reelection campaign that entire lines could become automated.
The RMT’s ballot comes just months after transport unions threatened to walk out during the Olympic and Paralympic games in a dispute over bonuses.