An information recording medium has a plurality of recording layers, one (L0 layer) of which has an identifier recording area (NBCA) containing an identifier for identifying the information recording medium. In the identification information recording area, a groove track (GT) is divided in the direction along the groove track by a spatial frequency not lower than a specified spatial frequency (2NA/?) at which reproduction becomes impossible according to the optical transmission characteristics (MTF) of a reproduction optical system.