To make it difficult to obtain an original image based on display data. An image display device includes an image set generating unit that generates a plurality of image sets S, each including a plurality of modified images Cj that are obtained by modifying an original image O, and an average of pixel values of corresponding pixels of the plurality of modified images Cj included in each of the image sets S corresponding to a value of a corresponding pixel of the original image O, and an image display unit for sequentially displaying the plurality of modified images Cj included in each of the image sets S by sequentially using the plurality of image sets S generated by the image set generating unit.