PURPOSE: To input properly a character to be written in an input area even when its locus deviates slightly from its frame by setting an effective input area enlarged with respect to an input area frame has detected presence of a pen tip and detecting character locus data in the area.

CONSTITUTION: When the pen tip touches a space within the input area 3' frame, a frame detecting circuit 20 detects the frame number (2, 2) of the input area 3' based on a coordinate signal (x, y) from an x.y coordinate detecting circuit 10 so as to store it in a register 30, sets the effective input area 3L wider than the area 3' frame through an effective area deciding circuit 60 and a gate 70. As long as one character in the effective area 3L is inputted, the coordinate signal (x, y) of the character is converted into a coordinate signal (X, Y) series standardized by an effective area coordinate converting circuit 80 through the gate 70, and is accumulated in a buffer memory circuit 90. The moment the accumulation is completed, the register 30 is cleared.