A server (1) analyzes request information from a client (11) by a request analyzer (4) and selects necessary image data from multiple viewpoint image data (2) to be output to an image generator (3). The image data is generated by interpolation and output to an image synthesizer (5), in which a plurality of images data is synthesized in a form suitable for encoding. An encoder (6) encodes the image data and transfers it to a network (7). The client (11) receives the encoded image data, decodes the data through a decoder (12) and outputs the decoded image data to an image processor (13), where it is converted into a stereoscopic display format and displayed on a display unit (14). The client (11) includes an input unit (16) for changing the viewpoint, and transmits the request information of viewpoint alternation to the network (7) by a request output unit (15).