PURPOSE: To eliminate the need for a page-by-page generating processing when background data which are common to all the pages of a prepared document are generated and to decrease the frequency of input operation and the amount of background data for the generating processing by performing a processing for expanding the background data of a kind specified at the time of the genera tion in all the pages of a document wherein normal page data are present.

CONSTITUTION: A ROM 3 stores various programs 3a required for the operation of a CPU 1 including a background data generation routine 1a which is common to all the pages, a page data expansion routine 1b, a density adjustment routine (c), and a document preparation routine 1d, and basic data of background data 3b. The CPU 1 generates the background data consisting of graphic data or character data common to all the pages of the normal page data and expands the background data by the pages of the normal page data within a page range based upon specific printing size at the time of print output. A printing part 6 prints the expanded background data in the same page of the normal page data and prints common data common to all the pages of the normal page data.