An image display apparatus includes a memory 1 having a first mode and a second mode in which image data are sequentially written and read per frame and per sub-frame area respectively, a compressor 10 capable of switching a compression output state and an uncompressed output state in which a compression image data and an uncompressed image data are outputted respectively, and a decompressor 20 capable of switching a decompression output state and a non-decompression output state. A controller 6 switches the compressor from the uncompressed output state to the compression output state during a first input vertical blanking period, switches the decompressor from the non-decompression output state to the decompression output state during a first output vertical blanking period immediately after the first input vertical blanking period, and switches the memory from the second mode to the first mode during a first output vertical blanking period.