The present invention is a mixed-reality system including a server and a portable terminal device, the portable terminal device having a display for displaying a virtual object to a user present in a predetermined real space and having a photographing device that photographs the real space, the mixed-reality system serving to display, on the display, a mixed-reality image in which the virtual object is superimposed on a photographed image of the real space, wherein, at each of one or more predefined positions on a real object present in the predetermined space, an MR marker constituted of an identification code containing position information corresponding to that position and an alignment marker having a polygonal shape is disposed. The server includes a virtual-space-data storage unit and an application storage unit, and the portable terminal device includes a browser unit, a marker recognition unit, a position determination unit, and an image generation unit.