The present invention enables program codes to be shared among processors 211. To prevent the debug operation of one processor 211 from affecting the debug operation of the other processors 211, when detecting a breakpoint during execution of a program code, a debugger 410 or a debugger stub 520 controls the execution of the program code while exchanging breakpoint information 800 with the other debuggers 410 or the other debugger stubs 520. Furthermore, a circuit 170 is created which prevents the program code being carelessly rewritten due to thermal runaway, a bug, and the like of a processor 211, and the protection setting by the protection logic 71 in the circuit 170 is released only in case the processor 211 accesses each of a plurality of registers from 65 to 67 in specified order.