Shared control is a challenge to combine and capitalize on both advantages of human and mechanized automatic controls. But any interventions by a machine-autonomy may introduce some kind of collapses in the isomorphism between the two different interaction fields of the human operation and of the system performance, which is necessary for the naturalistic involvement of a human operator with the system control. On this issue, we focus on the adaptability for the machine-autonomy to coordinate the mapping between the two fields to facilitate the human feeling of direct involvement with the system control, as well as the human adaptation (i.e., co-adaptation). In this chapter, we investigate their joint activity in a shared control of a virtual robot teleoperation environment, and then discuss the effect of the machine intervention in terms of the system operationality for human operators. The feasibility of the co-adaptive approach towards the well-coordinated relationship between a manipulator and a manipulatee is also examined based upon the experimental result with a simple adaptation algorithm implemented into the machine-autonomy..