A data processing system includes a plurality of data processing devices that perform in parallel data processing on the basis of initial setup data. The data processing devices each has a unique ID and includes a plurality of registers that store the initial setup data and a transfer circuit. The transfer circuit receives packets including a payload that is the initial setup data, shared information, a destination ID and a destination address and, when the shared information indicates that the payload is the initial setup data to be set commonly into the plurality of the data processing devices including its own data processing device, transfers the payload to the register that the destination address indicates irrespective of mismatching between the destination ID and its own ID.