GROOVE RECORDING OPTICAL DISK

PROBLEM TO BE SOLVED: To provide a phase change optical disk medium in which high density information reproduction is enabled by suppressing the cross erase of an adjacent track corresponding to an optical disk drive for recording/reproducing by a blue laser. SOLUTION: Grooves are formed on a substrate so that the width of a track formed on a projecting part between grooves is about 170 nm and the depth of the groove is 30 to 50 nm, a recording sensitivity is improved by increasing an effective energy absorption quantity on the track and the possibility of cross erase is reduced by reducing an effective light quantity in the groove through an optical interference effect due to the shape of the grooves. Therefore, the absorption quantity of energy is controlled by the shape of grooves on the optical disk, the effective energy absorption quantity is increased on the track and the recording sensitivity can be improved by reducing the distribution of the energy absorption quantity in the groove.