An information recording medium in which an access unit including basic data and extension data is recorded, so as to allow a decoder that decodes only basic data to process the access unit which includes the basic data and the extension data for the next generation.The information recording medium is an information recording medium on which a stream, having plural access units and including at least one of image and audio, is recorded, wherein: each of the access units has: a first packet which includes basic data; and a second packet which includes extension data related to the basic data; the basic data is data that is decodable in a completed state without requiring the extension data and the extension data is data for improving the quality of data generated from the basic data; and the stream includes information which indicates attributes of the first and second packet.