A visible image is formed on an optical disk by using an optical disk recording apparatus that forms a pit with a length defined by recording data (EFM-modulated data) by applying a laser beam onto the optical disk. At least a part of the recording data are replaced with the visible image forming data to generate the recording data containing visible image forming data. When the recording data containing the visible image forming data are recorded on the optical disk, the visible image forming data are extracted from the recording data to act as a gate signal. The visible image is formed by forming a pit defined by the recording data in an area of the gate signal.