PURPOSE: To improve the analysis efficiency of an action history by starting and stopping the storage of the action history when the coincidence of plural start conditions and stop conditions, which is previously set and the address of a micro program during execution is detected.

CONSTITUTION: First and second storage means 1 and 2 which respectively store plural addresses which are previously set, and first and second comparison means 3 and 4 which respectively compare the addresses stored in the storage means 1 and 2 with the address of the micro program during execution are provided. A control means 5 executes control for starting the writing of the action history into a storage means 8 when coincidence is detected in the first comparison means 3 and for stopping writing the action history when coincidence is detected in the second comparison means 4. Thus, the analysis efficiency of the action history is improved.