To give smoother opening/closing operation to a vehicle door.
This vehicle door drive mechanism comprises an electric driving source 51 arranged in the vehicle door 2, a rod member 54 turnably connected to the vehicle door 1, a rail mechanism 53 arranged in the vehicle door 2 for supporting the rod member 54 so as to be movable forward or backward from the vehicle door 2, and a power transmitting mechanism 52 arranged in the vehicle door 2 between the electric driving source 51 and the rod member 54 for giving constraining force of a preset value or greater to the rocking of the vehicle door 2 relative to a vehicle body 1 so that it is operated into a connected condition of transmitting the driving force of the electric driving source 51 to the rod member 54 or into a disconnected condition of precluding the transmission of the driving force of the electric driving force 51 to the forward/backward rod 54 for the rod member 54 to be moved forward or backward from the vehicle door 2 by the rail mechanism 53.
HATTORI TAKEMI
KOBAYASHI KIICHI
KUNIMATSU YUKINOBU