PURPOSE: To improve the efficiency of debugging by executing debugging on the basis of source program language while maintaining the debugging function.

CONSTITUTION: A source program in a source program file 1 is displayed on a display device 3 through a debugger body 2. A position corresponding to a bug on the source program part is corrected by the source program language. Correction control information corrected in accordance with said correction is recorded in a correction control table 4 and an object program part corresponding to the corrected source program part is stored in a corrected object program storing means 5. At the execution of the object program, the corrected object program part is executed while referring the corrected information in the correction control table 4.