PURPOSE: To attain self-restoration to normal reproducing without resetting a system when a data reading error occurs in a data expanded reproducing device at the time of compressing and transferring difference information.

CONSTITUTION: If a data reading error occurs at the time of recording an ADPCM compressed data block and a restoring data block in the 1st storage device 101 at an optional interval, a control device 105 outputs a transfer data address specifying signal to a data transfer control device 104 and ADPCM compressed data recorded in the 2nd storage device 113 are switched to restoring data, which are transferred. When an expanded reproducing device 106 is initialized and restored data are transferred from the device 104 to the initialized device 106, a scale level and a PCM value which are to be obtained at the time of normally reading the ADPCM compressed data generating a data reading error can be set up.