PURPOSE: To attain efficient processing of an image data in which a graphic data is mixed by generating a control signal accessing a storage means and writing an image data in the access mode designated by an access mode designating means into a storage means.

CONSTITUTION: In accessing a memory 101 from a bus 105, a mode designation signal representing whether the accessing is executed in the 1×k-dot line data mode or the m×n-dot block data mode is set and outputted to a signal line 104. When the access mode in the line data is designated, a control signal generating section 109 generates a write signal of the memory 101 for writing. The read from the memory 101 is executed conversely. When the access mode by the data is designated, the input data from a data bus 105b is used similarly as the block data for write/read.