A programming apparatus has a parameter storage section for storing parameters related to the operation control of an operating mechanism of an NC machine tool, a CL data storage section for storing CL data including data relating to a moving position of a tool and machining conditions, an NC program generating section for referring to the parameters in the parameter storage section, and generating an NC program form the CL data in the CL data storage section, and NC program storage section for storing the generated NC program. The NC program generating section checks whether the machining condition data included in the CL data is suitable by referring to the parameters, and, when it is not suitable, corrects the machining condition data using the parameters and then generates an NC program based on the CL data in which the corrected machining condition data is included.