Numerical control device

A numerical control device comprising:

• a program storage unit that stores therein machining programs of respective systems;
• and
• a program analysis unit that simultaneously executes the machining programs independently for each of the systems by analyzing the machining programs of the systems, wherein the machining program of each of the systems includes a control variable, which is a
• common command for the systems, and one common value among the systems is saved in the control variable,
• while the machining programs are simultaneously executed, in a case where the control variable is not being executed in a machining program of any of the systems, if execution of the a-control variable is started in a machining program of any of the systems, the program analysis unit permits only a system that has started the execution of the control variable to execute and overwrite the control variable, and does not permit another system other than the system that has started the execution of the control variable to execute and overwrite the control variable even when an attempt is made to execute the control variable in a machining program of the another system, and
• when execution of the control variable is completed in the machining program of the system that has started the execution of the control variable, the program analysis unit permits any one of the systems to execute and overwrite the control variable.