PURPOSE: To facilitate a format change processing and to improve an operability by applying a format change to sentence data in accordance with a stored format change content.

CONSTITUTION: An area is inputted from an input device 20. An area edition control means 14 operates layout information, such as an area position and an area magnitude, in accordance with the inputted area. This arithmetic information is stored in a layout memory means 11. Next, characters are inputted from the input device 20. The characters are edited to sentence data by a sentence edition control means 16 and stored in a sentence data memory means 13. A composition data operation means 18 operates composition data from the layout information and the sentence data. The operated composition data is indicated on a display device 32 through a display control device 15. On the other hand, an overflow detection means 2 receives the composition data from the composition data operation means 18 and detects whether all the characters are contained in the area; if the result is NO, it issues an instruction to a format change processing means 6.