To improve reliability of the circuit by simplifying the configuration so as to make the circuit small in size.

A new header generating section 12 generates a new header based on a time stamp extracted from packet data by a header decode section 11 and on auxiliary data relating to decoding. A new real data generating section 13 inserts a new header as a frame header of real data obtained by eliminating the header part from the packet data at the header decode section 11 in order to generate new real data and the data are stored once in a buffer section 14. A new real data decode section 15 reads the new real data from the buffer section 14 and decodes the fame real data in succession to the header so as to obtain expanded data based on the time obtained by collating the time stamp in the frame header of the new real data with a time information of a time stamp management section 16.