A plurality of images, in a layout based on a display protocol, is displayed with high efficiency. Display protocol sequences PS1, PS2 and PS3, in which multiple display protocols are lined up in a predetermined order, are remembered in a memory means of a workstation. The workstation is connected to an image server storing a plurality of image data, and by selecting a desired display protocol sequence and specifying to the image server to transmit image data, the layout is switched based on the display protocol sequence, and the images are laid out, etc. and displayed on a monitor.