PURPOSE: To improve efficiency in the use of memory and to accelerate an image processing device by allocating the required number of unit areas of a buffer area divided corresponding to the size of image data to be stored.

CONSTITUTION: A memory mapping circuit 3 attached on an image processing circuit 4 performs mapping by dividing memory 11 for image data storage into 64 pages setting 256KB as a unit. When data to apply the mapping is set on the memory mapping circuit 3, the logical addresses 0-63 of the image processing circuit 4 are used. A command string supplied from a CPU 1 holds map data, and the image processing circuit 4 recognizes the working status of the memory. The image processing circuit 4 itself performs the mapping processing autonomously by supplying an instruction to perform the rectangular area transfer of the image data to a null page.