Provided is a control apparatus which may apply an electric signal to a specific point or area selected from a plane or may receive the signal from the specific point or area. The control apparatus includes an upper electrode and a lower electrode. When it is intended that an electric field is applied to a point in which the upper electrode and the lower electrode come in contact with each other, an electrical bias is applied to the lower electrode, and the upper electrode is maintained in a non-connected state. When it is intended that the bias is selectively applied, the upper electrode is maintained in a grounded state. Therefore, transferring of the field from the lower electrode to a ground electrode disposed at a bottom is shielded, and thus transferring of the electric signal is also blocked.