The invention method and device for the automatic mounting of connector shells (5) and electric conductors (8) discloses that connector shells (5) are put on with the aid of an industrial robot (1) onto the contact parts (8.1, 8.2) of an electric conductor (8). A gripper tool (4) of the industrial robot (1) is capable to grip simultaneously several connector shells (5). Each contact part (8.1, 8.2) of the electric conductor (8) is maintained in rest position by two independently controllable gripper pairs (11.1, 11.2) of a double gripper (11) at the end of a cable-processing line (9), after a centering module (19) has set the desired position of the contact parts (8.1, 8.2). Depending on the intended device, the two contact parts (8.1, 8.2) of the electric conductor (8) can be simultaneously equipped with connector shells (5) by respectively one industrial robot (1), or successively by only one single industrial robot (1), with the aid of a transfer module (10), coordinated to the double gripper (11) and rotating the rotatable electric conductor (8). The error-free put-on of the connector shells, as well as a withdrawal motion required for the testing of the perfect contact seat, are surveyed by sensors. The finished, plugged-together cable harnesses (13) are for example transferred by two industrial robots (1), in a stretched state, individually, to a transport device (14) adapted to the length of the cable harness (13).