A data processing device for taking out necessary packet data from a sector in which a plurality of packet data exist in a mixed manner includes an audio decoder unit that has, in parallel, an audio packet extraction unit for extracting an audio packet made up of audio data with respect to an input of sector data from an external memory connected to a front-end processor unit, a supplementary packet extraction unit for extracting a supplementary packet made up of supplementary data, and a frame information extraction unit. Thus, when collectively providing the front-end processor unit and the audio decoder unit on one chip, a buffer memory for the frame state can be omitted.