It is conventionally known to create an NC tape for driving an NC machine tool by automatic programming, saving time and obtaining an accurate program.
However, when a program for machining a material 2 such as the round rod as shown in FIG. 1 with a two-saddle turret lathe to obtain a product having a hole 3 and an outer shape 1 is created by an automatic programming apparatus, it is necessary to determine which machining steps are to be performed by respective saddles and also whether machining can be performed by both saddles simultaneously. For example, the machining steps shown in FIG. 1 include rough cutting step N1 and finishing step N2 as outer-diameter machining, drilling step N3, rough cutting step N4 and finishing step N5 as inner-diameter machining of the hole formed by the drilling step N3, and rough cutting step N6 and finishing step N7 as face grinding. Among these, the rough cuttings steps N1, N4 and N6 can be performed simultaneously with the drilling step N3, but cannot be performed simultaneously with the finishing steps. Therefore, each machining step is assigned to a saddle. It is then determined which of the steps are to be performed simultaneously and when to start machining, thereby creating a program for each of the saddles.