A data processing device which, even if congestion occurs on a bus circuit of a specific processing circuit in an LSI in which multiple circuit modules are connected by buses, can fully actualize the performance potential of the system on chip. Buses and slave circuits on which accesses concentrate are provided with observation blocks. Each observation block has a mechanism to notify system control circuits such as a clock controller and master circuits such as CPU cores of the acquired status information, and each master circuit further has a mechanism capable of dynamically altering the priority order for notifying the bus circuits and slave circuits of the priority order of processing.