A formatter 2s13 is provided and, when a code sequence which matches a part (‘00’) of the head of a predetermined code sequence detected by a start code prefix detection unit 2s3, is detected, the start code prefix detection unit 2s3 detects the residual part (‘00’, ‘00’, ‘01’, ‘E0’) of the detected predetermined code sequence to detect a pattern of (‘00’, ‘00’, ‘00’), and the formatter 2s13 outputs one (‘00’). After the boundary of packets is defined, amongst data which are not transferred to a decoding buffer 2s9, data corresponding to code sequences other than the code sequence (‘00’, ‘00’, ‘01’, ‘E0’) indicating the packet boundary are output to the decoding buffer 2s9. Therefore, when separating a coded and multiplexed signal, control of an input buffer reading control circuit 2s4 is simplified, and thereby the hardware scale is reduced, resulting in an inexpensive apparatus for reproducing a digital code sequence.