An image data processor for generating driving image data for operating an image display device, including: an image memory; a write-in control section for sequentially writing-in plural frame image data having a predetermined frame rate to the image memory; a read-out control section for reading-out the frame image data 1 times (1 is an integer of 2 or more) at a rate 1 times the frame rate with every frame image data written into the image memory; and a driving image data generating section for generating the driving image data corresponding to each read-out image data sequentially read out of the image memory.