PURPOSE: To print image data whose size is larger than the size of a DMA space with respect to the print controller which transfers image data on a memory to a printer by DMA to print it after mapping the image data in the DMA space on a virtual memory.

CONSTITUTION: First, an initial block formed by an initial block forming means 10 is mapped in the DMA space. Mapped data is successively transferred by a DMA control means 3, and a mapping control means 6 and a mapping means 2 map unmapped image data in the idle area of the DMA space to successively form blocks while unmapping blocks whose transfer is completed. At this time, the end of the mapping processing is reported before the completion of transfer of the just preceding block to form blocks without delay. Blocks are continuously transferred by the command of a DMA relay means 9.