PURPOSE: To conduct rotation modification of a character string by calculating a coordinate of the character string according to a rotation angle and expanding the character string along the coordinate.

CONSTITUTION: The device is provided with an input designation section 11 designating a character string to be rotated, a character string data buffer memory section 16 deciding the rotation reference of the character string designated by the input designation section 11 and storing the character string as a head of the rotation reference, a coordinate calculation section 14 calculating the coordinate of the character string stored in the character string data buffer memory section 16 according to the rotation angle, an expansion processing section 15 expanding the character string to the coordinate calculated by the coordinate calculation section 14 and a display section 13 displaying the character string expanded by the expansion processing section 15.