PURPOSE: To restrain a process for detecting the input of an ineffective point on a host and lighten the load of an input process on the host, and to easily make visual corrections by ANDing the display signal from a high-order device which is displayed at a display part with the detection signal of an input position from an operation part.

CONSTITUTION: For example, the display signal (VDT) from the host and the detection signal Y from a touch panel 2 are ANDed to make the detection signal from an undisplayed part ineffective. Further, an attribute signal (r, g, b) corresponding to a color display signal (R, G, B) is stored in the bit map memory of, for example, a display control part 3, and the color display signal (VDT) D (R, G, B) from the display control part 3, attribute information Da (r, g, b) of the display signal D(R, G, B), and the detection signal Y from the touch panel 2 are ANDed. Consequently, whether the input position on the touch panel 2 is effective or ineffective can be specified with the attribute information Da of the display signal, e.g. color (R, G, B).