PURPOSE: To make a digital mobile communication equipment compact and light in weight by performing voice codec processing with the DSP of one chip and reducing the capacity of a memory built in the DSP less than the conventional capacity concerning a buffer for inputting/outputting PCM data.

CONSTITUTION: When decoding is started, an encoded data sequence 111 is received and inputted to a buffer 112 for receiving the encoded data sequence. Decoding frame processing 113 is performed to the received data sequence 111. Next, decoding sub frame processing is performed at a decoding sub frame processing 114, decoded PCM data 102 are outputted to a buffer 103 for inputting/outputting the PCM data, and the same processing is performed at a decoding sub frame processing part 115. Afterwards, when encoding processing is started, the PCM data 102 inputted at a certain sampling interval and stored in the buffer 103 are provided just for one frame, and encoding frame processing 104 is performed. Thus, encoding/decoding is performed by the DSP of one chip, and the capacity of the memory built in the DSP can be reduced.