To provide a setting method for initial conditions of working program with which there is no trouble such as external program search or command line input and a problem such as the selection error of subprogram or the unexpected reload of working program is not generated, either.

An initial setting program for setting initial setting data or previously operating a machine tool is previously stored on a hard disk 75 corresponding to the name of working program so that the initial setting program can be started while referring to the name of working program as an execution object. Besides, the initial setting program is run while reading the working program so that the erasure of parameter such as a modal code set by the initial setting program can be prevented and the working program can be executed just after the execution of initial setting program.