PURPOSE: To give an operating instruction to a computer in natural feeling for humans by instructing directly a position on a screen, and to execute the bidirectional transmission of information between the humans and the computer by executing operation for coordinate position information based on the operating instruction shown by state information.

CONSTITUTION: The state information generated by a switch 28 is transmitted to the computer through a data line 30. An operation information display part 32 gives operation information showing the operating state of the computer from the computer through the data line 30, and the display part 32 displays the operation information. Accordingly, the selection of a menu or the movement of a graphic, etc., can be realized more naturally for the humans by the detection of the coordinate position information and the switch 28 provided on a pointing pen 14, and simultaneously, since the bidirectional information transmission between the humans and the computer is executed by displaying the function of the switch 28 by the operation information display part 32, a more natural and comfortable human-machine interface can be constructed.