An automatic programming device which prepares, with a 2-spindle machine having first and second spindles and a 1-spindle machine having a first spindle only as controlled objects, a machining program for machining with an NC device a machining area determined by using a material model and a product model, wherein whether a machine tool as a controlled object is a 2-spindle machine or a 1-spindle machine is judged, and, based on the judged result, an automatic program for the 1-spindle machine or an automatic program for the 2-spindle machine is operated.