PURPOSE: To enable an automatic mode setting without being conscious of whether a entry direction is to be horizontally long or vertically long, by detecting the inclination of a tablet and recognizing the inclination direction by a CPU.

CONSTITUTION: When a user performs a tablet input with a pen by holding an information input device 120 in a horizontal state by hand, be uses the device in a state that a side C 103 is made to be placed in front of the user and a side A 101 is inclined higher than the side C 103 in almost all cases. By detecting this state by an inclination sensor 12 and transmitting inclination data to CPU 1, the CPU 1 recognizes the state that the side A 101 is inclined higher than the side C 103 and judges that an entry area should be used in a horizontal type. The display format of a CRT 7 is set to a lateral type and the data inputted subsequently from the input tablet 11 is judged as the one corresponding to the horizontal type. Thus, even if the vertical type and horizontal type modes are not consciously set at the time of the first input, the input of graphics and characters automatically becomes possible.