Each of the panoramic images corresponding to a plurality of positions of a viewpoint is compressed and stored as partial images obtained by dividing each panoramic image by a predetermined field of view. The panoramic image has a field of view wider than a display field of view of an image to be displayed on a display unit. A partial image containing an image to be reproduced is selected based on the information about the position and the direction of a viewpoint and the display field of view, and an image corresponding to the position and the direction of a viewpoint is generated and displayed from the selected partial image. Thus, when virtual space in the walk-through system is designed using the IBR technology, stored image data can be efficiently reproduced.