An image suitable for an image acquisition client device which accesses an image registration/transmission server 10 is displayed relatively quickly. Image data representing images suitable for display on the image acquisition client device which accesses the image registration/transmission server 10 are previously generated and stored in an image database 25. When a request to transmit the image data is issued to the image registration/transmission server 10 from the image acquisition client device, the image database 25 is searched for the image data representing the image suitable for the display on the image acquisition client device. The image data searched for is transmitted to the image acquisition client device. Since the image data suitable for the display on the image acquisition client device are previously generated, and the image data suitable for the display is transmitted when the image acquisition client device accesses the image registration/transmission server 10, the suitable image can be quickly displayed.