Visible image unit identification code structure

This invention relates to a visible image unit identification code structure using a spatial visible image forming device. A spatial visible image forming device is used that includes: a laser source that emits a laser beam in an invisible region; a scanning means that scans the laser beam; a condensing optical system that condenses the laser beam to a drawing scheduled point in a space so as to cause plasma emission of a gas; and a control means that controls oscillation timing of the laser source and scanning timing of the scanning means so as to generate the plasma emission at the drawing scheduled point in a time series and draw a visible image as an afterimage phenomenon of the plasma emission. A visible image unit identification code formed by combining and arranging multiple kinds of multiple visible image units in different states including different lightnesses/darknesses, colors or shapes or the like is displayed in a space such as in air or in other gases or in water, and information can be transmitted by reading the visible image unit identification code using a reading means from any direction.