The present invention relates to a read-once record medium, comprising: a data substrate, having control data zone and a data zone, and said having pre-record data; a sensitive layer, disposed above said data substrate; a refractive layer, disposed above said sensitive layer; an adhesive layer, disposed above said refractive layer; and a transparent substrate, disposed above said adhesive layer; thereby, the structure of said sensitive layer or said data substrate will be changed when laser beams with specified 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. Furthermore, the present invention also provides a system with read protecting function.