Upon receiving an erase command for data recorded in a write-once optical disc, an information recording device corrupts data in an information area (synchronization signal in Run-in, frame synchronization signal, address information and the like), in an erased area on the optical disc, in which information necessary for synchronization of reproducing data by overwriting the data in the information area with an erasing pattern. The erased area is specified by an erase starting position and a size of data to be erased. In this way, the information recording device erases the data in the erased area.