PURPOSE: To prevent a printed matter from being cut into small pieces by switching the subject of printing to the print data of the highest priority when the printing progresses up to the switching page position that is previously set.

CONSTITUTION: A schedule part 38 includes a print propriety deciding part and a data selecting part. The data selecting part selects the divided data that has the highest priority and is to be printed next based on a schedule management table. The print propriety deciding part decides whether the printing of the divided data is possible or not based on the value of the print parameter stored in an attribute management part 35 and according to the state of the printing part 15 that is detected by a print environment detecting part 39. Thus the divided data that has the highest priority is selected among those printable divided data. Then an output control part 45 reads the divided data selected by the part 38 out of a storage part 32 and sends it to the part 16 for printing.