PURPOSE: To prevent the erroneous position detection and to accurately detect the position by performing the arithmetic operation by a position signal which is obtained by checking the contact resistance between the resistance film of an upper sheet and the resistance film of a lower sheet for several times in the prescribed time.

CONSTITUTION: The resistance film is printed on the surface with opposted two PET sheets of a tablet 1 and electrodes X1 and X2 are deposited to one resistance film. Electrodes Y1 and Y2 crossing at right angles with the electrodes are deposited on the other resistance film. A controller 3 controls the signals of these electrodes and a processing circuit 2 detects the control position of the tablet 1 to output the position coordinates to the host information processing equipment. In this case, the processing circuit 2, when judging that the two resistance films are surely contacted, performs the open check after detecting the position data in the X direction and detects the position data in the Y direction when judging the enough contact. The operation is performed several times in the prescribed time and the arithmetic processing is performed based on the acquired position data and is outputted to the host information processor.