PURPOSE: To output graphic data with variable density by accumulating charge corresponding to a voltage in ferroelectrics arranged on a table face in a matrix in the X and Y directions by means of a writing brush-like input pen.

CONSTITUTION: Power supply voltage is applied to the brush 231 of the input pen 23. When the surface of the tablet 11 is traced by the pen 23 in said status, the voltage is applied to ferroelectrics 12 existing in the traced area and charge is generated. The generated charge is increased/decreased in accordance with the applied voltage. Thereby, a graphic signal based upon an analog voltage can be obtained by extracting the voltage impressed to the X and Y electrodes in the ferroelectrics 12 by multiplexers 13, 14. When the surface of the tablet 11 is traced by the input pen 23 while changing its voltage, charge is simultaneously generated in the plural ferroelectrics 12, these charge values can be extracted as a voltage to use as the input of tablet face, and the variable density of a graphic can be expressed by the voltage levels.