A recording medium which realizes high sound quality and is playable on a conventional playback device has a recording layer provided with a double-layered structure having at least a first layer L1 and a second layer L2, an audio data program is recorded on the first layer in the first data format, which is the conventional format, and the audio data program is recorded on the second layer in a second, new data format. The audio data programs recorded on the first layer and on the second layer are the same program and can be produced using 1-bit DELTA SIGMA modulation having a high sampling rate as the new format, the DELTA SIGMA modulated signal being passed through successive decimation filters to form the lower sampling rate signal of the conventional format. The double-layered disk can be played back using a disk judging unit that detects the disk's table of contents and controls a laser beam focus of a pick up, an operating clock frequency, and the decoder for reading out the data recorded in pits formed on the disk.