PURPOSE: To realize efficient practice of typing by displaying an error input key and a correct input position in key arrangement on a display tube and thus showing position relation in the actual key arrangement evidently, and recognizing the correct positions of fingers without looking at a keyboard.

CONSTITUTION: The keyboard 2 has arrays of keys 2-1 for inputting characters and symbols. The same arrangement 1-1 as the key arrangement on the keyboard is displayed on the display tube 1 by utilizing the line drawing function of a CPU which is not shown in a figure. A character string (1-2) of "a", "i", "u"W is an example to be displayed on the dislay tube and if some key is hit erroneously, the position and contents of the hit key appear at the display part 1-1 of the display tube 1. Consequently, the relation between the correct key and error key is discriminated on the display tube 1 without looking at the keyboard 2, and consequently error corrections are facilitated to realize efficient practice of typing.