A device for automatically mounting a connector-housing with a contact-part attached to an electrical line includes a holder, a movable-gripper, an alignment-station, a camera, and a control-device. The holder fixes the connector-housing. The movable-gripper holds the contact-part and inserts the contact-part into a cavity of the connector-housing. The alignment-station includes an alignment-gripper that holds the contact-part and rotates the contact-part about a rotation-axis parallel to an insertion-direction. The camera determines an actual-rotational-position of the contact-part held by the alignment-gripper in relation to the rotation-axis. The control-device compares the actual-rotational-position with a predetermined-rotational-position based on the characteristics and arrangement of the connector-housing. The control-device further controls the alignment-gripper to perform a corrective rotational movement based on the result of the comparison.