PURPOSE: To facilitate the check of trace and to prevent the throughput of a computer from being lowered by the trace by reading an instruction after the virtual address of the instruction to be executed is stored in a trace memory.

CONSTITUTION: A virtual memory control mechanism 80 reads the virtual address of the instruction to be executed from a program 20 and reads the instruction at the virtual address after the address is stored in an instruction execution address tracer 60. A memory 30 is equipped with blocks 31-33 storing the process part of the program 20, and the virtual addresses of the memory blocks 31-33 or the virtual address of a data part 24 is stored in blocks 21-24 of the program 20. When executing the instruction, the virtual memory control mechanism 80 checks a control table 40 corresponding to the virtual addresses 21-23 of the process part containing the instruction, generates interruption when no operation is executed, reads the virtual addresses 21-23 or the like of the process part and sets them to a fault ID 50.