A motorized split-hinge device for a very heavy double door, designed to be motorized and including a flap that is mounted to pivot around an essentially vertical axis of rotation on a frame, includes a stationary split-hinge part integral with the frame and a movable split-hinge part integral with the flap and mounted in rotation relative to the stationary split-hinge part around a pivoting shaft. The movable split-hinge part includes a drive mechanism driven by a motor unit adapted to drive the movable split-hinge part in rotation around its pivoting shaft and starting the flap moving by pivoting when opening or closing, whereby the motor unit is mounted in a removable manner on the drive mechanism and on a stationary part of the door, and is kept in drive position of the mechanism with anti-rotational locking relative to the flap.