PURPOSE: To shorten a debugging cycle by providing a filing function at the debugging system to control a target machine as a device to be debugged from a host machine as a debugging device through a communication line.

CONSTITUTION: An executing form program prepared by a software 10 for filing execution at a host machine 1 is loaded through a communication line 3 to a target machine 2 by the software for debugging execution. This program is debugged by the software for debugging execution, the source of program problems discovered during debugging is corrected at that site by the software 10 for filing execution, and the executing form program is prepared again. This operation can be realized on the same machine until the end of debugging.