An image display unit capable of displaying image data page-wise includes: a scanner portion; a display panel for displaying input image data in preview representation; an input condition determiner that compares the image data successively input through the scanner portion, as to input condition and determines whether there is any change in the image data input condition; and a display controller that, when the input condition determiner determines that the input image data has changed in the input condition, makes control such as to display the image data that was determined to have changed in the input condition and the image data input immediately before the image data in question, together on the display panel.