A vehicle door opening/closing apparatus includes a drum unit disposed on the side of one face of an inner panel constituting a vehicle door and including a take-up drum capable of taking up a length of cable disposed between the vehicle and the vehicle door, a drive unit disposed on the side of the other face of the inner panel and configured to drive the take-up drum, a power transmission mechanism configured for transmitting a rotational drive force of the drive unit to the take-up drum, with allowing engagement and disengagement between take-up drum and the drive unit, and a coupling mechanism for coupling the drive unit to the drum unit, with the inner panel being clamped there between.