PURPOSE: To move freely an optional format mark by a simple key operation, by specifying a desired format mark by format change instruction information and cursor position information, and storing a moving destination of the format mark.

CONSTITUTION: In accordance with a document data inputted from a keyboard 10, a control part 11 generates a document by a main storage part 12, and also displays a document generating state, for instance, on a picture display part 13 constituted of a CRT. Also, the control part 11 prints the generated document by a printer part 14 in accordance with an instruction from the keyboard 10. When a format change instruction signifying a movement of a format mark is received from the keyboard 10, the control part 11 executes format change processing to the document of the main storage part 12, and also displays its processing state on the picture display part 13. The control part 11 executes the format change processing in accordance with a program stored in an ROM 15.