A visible light characteristic changing layer is formed in a location which can be viewed from a part of a label surface of an optical medium. The optical medium is set on a turntable of an optical disk unit, which may be rotated at a constant angular velocity, while the power of a laser beam is modulated in accordance with image data. The optical pickup operates at a first power level when changing a visible light characteristic of the optical medium to form the visible information and the optical pickup operates at a lower power level when not changing a visible light characteristic of the optical medium. As a result, a visible-light reflectivity of the visible light characteristic layer is changed, thereby forming an image corresponding to the image data on the label surface, A tracking servo operation is turned off while the optical pickup forms the visible information.