To flexibly exchange data between DSPs by using a data buffer means connected to a common bus to exchange data among plural DSPs and controlling the exchange order of data between DSPs by an interrupt signal.

Plural units constituting a voice codec 5 consists of DSPs, and a bus to which DSPs are connected and a data buffer means where data buffer areas provided in a RAM 3 corresponding to respective DSPs are set are provided. When terminating execution of a processing unit, the DSP outputs obtained output data to the corresponding data area of the data buffer. The DSP which should execute the next processing unit is informed by the interrupt signal; and when the interrupt signal is inputted, prescribed data is read in from the data area or the data buffer means corresponding to the DSP of the occurrence source of the interrupt signal, and the prescribed processing unit is executed.