Information recording medium, authenticity checking and reading method therefor

The present invention relates to an information recording medium (1) on which information signals are recorded on the signal surface of a disc plate across a plurality of sectors in units of sectors and each of the plurality of sectors has at least a sector address and sector data. In particular, this information recording medium (1) includes a first sector part (area X), which includes at least one sector, and a second sector part (area Y) which includes at least one sector having a sector address (n-4, n-3, n-2, n-1, n) equal to the at least one sector in the first sector part but containing different sector data (Y-4, Y-3, Y-2, Y-1, Y).