A data processing device includes a computing circuit that accesses a peripheral device connected to through a internal bus, an internal bus connection circuit that is provided between the computing circuit and the internal bus, and switches an enable and a disable state of an access from the computing circuit to the internal bus, an exception notification controller that outputs an exception occurrence notification signal to the computing circuit based on an error occurred in the peripheral device, and a bus disablement controller that instructs the internal bus connection circuit to disable an access from the computing circuit to the internal bus in accordance with the notification of the exception occurrence notification signal, and instructs the internal bus connection circuit to cancel the disablement of the access in accordance with a start of an exception processing based on the exception occurrence notification signal.