The sampling frequency of a digital signal is converted from 96 kHz to 48 kHz for each frame by a down-sampling unit (13). The signal converted is compressed/encoded and output as a main code Im. A local signal corresponding to the main code Im is converted to a signal of sampling frequency of, for example, the original 96 kHz by an up-sampling unit (16) and an error signal between the this signal and an input digital signal is generated. Bits of a sample string of error signals are rearranged by rearrangement/encoding unit (18) and output as an error code Pe. At a decoding side, by using the main code Im and the error code Pe, it is possible to obtain a highly faithful reproduction signal or a reproduction signal based only on the main code Im.