Viewing of a scrolled image on a display screen is facilitated. Assume that a first image portion (81) is being displayed on the display screen of a mobile telephone and that a second image portion (82) is not being displayed on the screen. If scrolling is performed rightward in order to display the second image portion (82) on the display screen, data representing the scrolling direction and scrolling amount is transmitted from the mobile telephone to an image server. The image server rotates the second image portion (82) in accordance with the scrolling direction, reads the rotated second image portion (82) block by block and transmits the resultant image data to the mobile telephone block by block. The mobile telephone rotates the block images reversely through the angle of the original rotation and displays the blocks in order. The second image portion (82), which was not being displayed on the display screen, is displayed along the scrolling direction from the portion contiguous to the edge, in terms of the scrolling direction, of the first image portion (81) that is being displayed on the display screen.