PURPOSE: To improve the operability of the titled system, by setting the counting result of the number of times of interruption at each interruption point in an interruption frequency data area and processing a request for designation of the name of said data area by reference to the data area.

CONSTITUTION: A number of times of interruption counting part 18, a number of times of interruption setting process part 19 and a debugging instruction execution processing part 20 are added to an interruption point processing part 17 of a debugger 13. Then the interruption points 12A, 12B... are set into a program to be debugged with the debugging instructions given from a work station 24. At the same time, the interruption point control tables 21A, 21B and so on are produced. The value of a counter 22A of the table 21A is counted by the part 18 for execution control of the point 12A. Then the counting contents are set in a number of times of interruption data area 23 at every interruption point. When an instruction is received from the station 24 for the designating display of the name of the area 23, the debugging instruction is processed by reference to the area 23.