A device and method for demultiplexing in a digital broadcasting receiver for processing packet data configured by a packet header and a payload. A buffer buffers input packet data. Processors are parallel connected to the buffer. A packet header processor checks a packet header, identifies presence of adaptation information, and generates a control signal according to the presence of the adaptation information. An adaptation information processor processes the adaptation information of buffered payload data under control of the packet header processor. A packetized elementary stream (PES) header processor processes a PES header of the buffered payload data under the control of the packet header processor. A data processor generates an audio or video elementary stream (ES) from audio or video data of the buffered payload data under control of the PES header processor, and outputs the generated audio or video ES to an associated decoder.