To solve the following problems: when finding a problem in a program code and correcting it when copying and parallel-developing a program, there is a possibility of having to add the same correction even to another copied code, but a file copy or tracing of a history of revision cannot be easily executed, and the tracing cannot be performed when a copy of a line unit is performed; and when a character string such as a variable name on the code is revised, it cannot be found in character string retrieval, and there is a possibility that correction leakage occurs in similar problem to be corrected.

This program file management system numbers an ID in each line of a program file, and has management information into which the ID is turned over in time of the copy or the revision. The code copied or revised by the ID can be tracked to extract a correction part without exception.