The present invention relates to a read-once record medium that comprises a data substrate, a sensitive layer; a reflective layer, an adhesive layer and a transparent substrate; thereby, the structure of the sensitive layer or the data substrate will be changed when laser beams with specific power emitted from an optical storage device pass through the data substrate and focus on the sensitive layer, and the laser beams will be reflected by the sensitive layer and can not be recognized by the optical storage device.