Abstract: An image data processing device includes a first memory having a plurality of memory blocks for storing image data, a designator for designating an image data to be erased, an evacuator for temporarily evacuating image data other than the designated image data from a sharing memory block in which at least a part of the designated image data is stored, an erasure for erasing the designated image data from the memory block, and a controller for causing the temporarily evacuated image data and a new image data to restore in an emptied memory position.