PURPOSE: To input coordinates by the behavior of a left foot having the lowest scanning frequency by providing a foot position detecting means and an operation switch for determining the display contents of a display unit.

CONSTITUTION: The coordinates of the left foot position of a driver placed on a coordinate input part which inputs plane coordinate information to a display unit 51 for an on-vehicle computer are detected by an X-axial detection part 33 and a Y-axial detection part 34, and an X-axial detecting circuit 48 and a Y-axial detecting circuit 49. A computing element 50 sends the signal of this position information to the display unit driving part 52 of a display part 3. A cursor is displayed on the display unit 51 according to the position signal. The cursor is moved to a display position matching desired operation by moving the left foot over a look at the display unit 51 and the 2nd switch 45 of the coordinate input switch 2 is depressed. The display driving part 52 is stored with operation contents to be performed according to an X coordinate value and a Y coordinate value when the switch 45 for an operation determination signal is turned ON. Consequently, the storing operation is performed and a specific display is made on the display unit 51.