A camera system incorporating a seamless lens-drive switching mechanism includes a lens drive ring, a manual operation ring, a motor, a first one-way rotational transfer mechanism preventing the manual operation ring and the lens drive ring from being connected with each other in a first neutral state, and maintains the first neutral state even if the lens drive ring is rotated by the motor; a second one-way rotational transfer mechanism which prevents the motor and the lens drive ring connecting with each other in a second neutral state, connects the motor with the lens drive ring when the motor rotates from the second neutral state, and maintains the second neutral state even if the lens drive ring is rotated by the manual operation ring; and a controller which stops and reverses the motor to bring the second one-way rotational transfer mechanism into the second neutral state.