PURPOSE: To perform synthesis by easily and precisely matching the size and arrangement of the image of an input character by deciding either the size and the position relation of the input character setting either the size and the position relation of an existing character image in image data as reference.

CONSTITUTION: Fine adjustment is applied so as to match the size, etc., of an input character frame 22 displayed on the screen of a display part 15 with an existing character M, and a character synthesis processing part 10 and an image processor 12 perform desired processing such as the magnification/ reduction of the input character (m) by an operator precisely based on the size of the character frame 22a of the character input frame 22, and the values of an inter-character gap 22b and an inter-row gap 22c. Thereby, it is possible to precisely and easily perform the synthesis of the input character (m) matched with the existing character M, for example, without preparing a large number of character fonts with different size even when the various kinds of size of the existing character M and character gaps/row gaps exist.