PURPOSE: To improve the operability of the tablet device and to accurately input a specified coordinate by detecting pen pressure based upon a specifying means on a tablet and generating a trigger signal in accordance with the pen pressure.

CONSTITUTION: A pen pressure detecting part 3 holds voltage VP obtained from a conductive plate 27 and compares the voltage VP with a reference voltage Vref. When a plotting plate 10 is pressed by the pen pressure higher than normal pressure, the voltage VP becomes higher than the Vref and a high level trigger signal ST is outputted. In the case of the normal pen pressure, a low level trigger signal ST is outputted. The signal ST is supplied to a CPU 1 through a terminal 15 and a system bus 2. A coordinate detecting part 4 alternately closes switch circuits 31, 32 or 34, 35 and holds voltage generated in the plate 27 to form voltage corresponding to the input coordinate of the tablet 6.