A hologram of a virtual object or an object which actually exists is formed and a solid image is displayed. 3-dimensional information of the object to be displayed is divided into regions in the depth direction. Depth images are formed as 2-dimensional images where are seen from a plurality of points which are obtained by finely dividing the hologram forming surface for every region. A phase distribution at the hologram forming surface is calculated from the depth images and displayed on a liquid crystal display or the like as an electronic hologram. A reference light is irradiated onto the display and is converted into an optical wave front, thereby displaying a solid image. When forming a hologram recording medium, a zone image corresponding to each of the finely divided exposure regions of a dry plate is exposed multiple times.